Illumination optical assembly, exposure apparatus, and device manufacturing method

ABSTRACT

An illumination optical system can form a pupil intensity distribution with a desired beam profile. The illumination optical system for illuminating an illumination target surface with light from a light source is provided with a spatial light modulator which has a plurality of optical elements arrayed on a predetermined surface and individually controlled and which variably forms a light intensity distribution on an illumination pupil of the illumination optical system; a divergence angle providing member which is arranged in a conjugate space including a surface optically conjugate with the predetermined surface and which provides a divergence angle to an incident beam and emits the beam; and a polarizing member which is arranged at a position in the vicinity of the predetermined surface or in the conjugate space and which changes a polarization state of a partial beam of a propagating beam propagating in an optical path.

TECHNICAL FIELD

The present invention relates to an illumination optical system, anexposure apparatus, and a device manufacturing method.

BACKGROUND ART

In an exposure apparatus used in manufacture of devices such assemiconductor devices, light emitted from a light source travels througha fly's eye lens as optical integrator to form a secondary light source(which is generally a predetermined light intensity distribution on anillumination pupil) as a substantial surface illuminant consisting of alarge number of light sources. The light intensity distribution on theillumination pupil will be referred to hereinafter as “pupil intensitydistribution.” Furthermore, the illumination pupil is defined as aposition such that by action of an optical system between theillumination pupil and an illumination target surface (a mask or a waferin the case of the exposure apparatus), the illumination target surfaceis kept as a Fourier transform surface of the illumination pupil.

Light from the secondary light source is condensed by a condenseroptical system and thereafter illuminates the mask with a predeterminedpattern formed thereon, in a superimposed manner. Light transmitted bythe mask travels through a projection optical system to be imaged on thewafer, whereby the mask pattern is projected (or transferred) onto thewafer. Since the pattern formed on the mask is micronized, it isindispensable to obtain a homogeneous illuminance distribution on thewafer, in order to implement accurate transfer of the microscopic patteronto the wafer.

There is the conventionally-proposed illumination optical system capableof continuously changing the pupil intensity distribution (and, in turn,an illumination condition) without use of a zoom optical system (e.g.,cf. Patent Literature 1). This illumination optical system uses amovable multi-mirror composed of a large number of microscopic mirrorelements which are arranged in an array pattern and inclination anglesand inclination directions of which are individually driven andcontrolled, to divide an incident beam into microscopic unitscorresponding to respective reflective faces and deflect divided beams,thereby to convert a cross section of the beam into a desired shape or adesired size and, in turn, to realize a desired pupil intensitydistribution.

CITATION LIST Patent Literature

Patent Literature 1: U.S. Pat. Published Application No. 2009/0116093

SUMMARY OF INVENTION Technical Problem

Since the conventional illumination optical system uses a spatial lightmodulator having a plurality of mirror elements postures of which areindividually controlled, degrees of freedom are high for change incontour shape (which is a general concept embracing the size) of thepupil intensity distribution. However, for realizing a desiredillumination condition suitable for transfer of a microscopic pattern,there are demands for forming the pupil intensity distribution with adesired beam profile, in addition to the desired contour shape.

The present invention has been accomplished in light of theabove-described problem, and it is an object of the present invention toprovide an illumination optical system capable of forming a pupilintensity distribution with a desired beam profile. It is another objectof the present invention to provide an exposure apparatus and a devicemanufacturing method capable of transferring a microscopic pattern ontoa photosensitive substrate under an appropriate illumination condition,using the illumination optical system for forming the pupil intensitydistribution with the desired beam profile.

Solution to Problem

In order to solve the above problem, a first aspect provides anillumination optical system for illuminating an illumination targetsurface with light from a light source, the illumination optical systemcomprising:

a spatial light modulator which has a plurality of optical elementsarrayed on a predetermined surface and individually controlled, andwhich variably forms a light intensity distribution on an illuminationpupil of the illumination optical system;

a divergence angle providing member which is arranged in a conjugatespace including a surface optically conjugate with the predeterminedsurface and which provides a divergence angle to an incident beam andemits the beam; and

a polarizing member which is arranged in a predetermined space includingthe predetermined surface or in the conjugate space and which changes apolarization state of a partial beam of a propagating beam propagatingin an optical path.

A second aspect provides an illumination optical system for illuminatingan illumination target surface with light from a light source, theillumination optical system comprising:

a spatial light modulator which has a plurality of optical elementsarrayed on a predetermined surface and individually controlled, andwhich variably forms a light intensity distribution on an illuminationpupil of the illumination optical system; and

a divergence angle providing member which is arranged in a conjugatespace including a surface optically conjugate with the predeterminedsurface and which provides a divergence angle to at least a partial beamof a propagating beam propagating in an optical path, to generate aplurality of beams with different divergence angles.

A third aspect provides an exposure apparatus comprising theillumination optical system of the first aspect or the second aspect forilluminating a predetermined pattern, which implements exposure of aphotosensitive substrate with the predetermined pattern.

A fourth aspect provides a device manufacturing method comprising:

performing the exposure of the photosensitive substrate with thepredetermined pattern, using the exposure apparatus of the third aspect;

developing the photosensitive substrate on which the predeterminedpattern has been transferred, to form a mask layer in a shapecorresponding to the predetermined pattern on a surface of thephotosensitive substrate; and

processing the surface of the photosensitive substrate through the masklayer.

A fifth aspect provides an illumination optical system for illuminatingan illumination target surface with light from a light source, theillumination optical system comprising:

an input device for implementing input of light quantity distributioninformation of a target image on a first surface;

a spatial light modulator having N (N is an integer larger than K)optical elements which guide the light from the light source torespective local regions at positions variable on the first surface andwhich can be divided into K (K is an integer of not less than 2) opticalelement groups;

K filter portions which control variables about states of the localregions in K groups guided to the first surface by the K optical elementgroups, group by group;

an arithmetic unit which determines N first values of the positions andN1 (N1 is an integer not more than N and larger than K) values of thevariables of the local regions, depending upon an error between a firstimage obtained by arranging N aforementioned local regions on the firstsurface and the target image, which divides the N local regions into theK groups depending upon the N1 values of the variables, and whichdetermines common second values as values of the variables for therespective K groups; and

a condenser optical system which sets the positions of the correspondinglocal regions for the respective K optical elements, to the first valuesand sets the variables to the second values and which illuminates theillumination target surface with light from a light quantitydistribution of a second image formed on the first surface.

A sixth aspect provides an exposure apparatus for illuminating a patternwith exposure light and implementing exposure of a substrate with theexposure light via the pattern and a projection optical system, theexposure apparatus comprising:

the illumination optical system of the fifth aspect,

wherein the pattern is illuminated with the exposure light by theillumination optical system.

A seventh aspect provides a device manufacturing method comprising:

forming a pattern of a photosensitive layer on the substrate, using theexposure apparatus of the sixth aspect; and

processing the substrate on which the pattern has been formed.

An eighth aspect provides a method for forming an image, the methodcomprising:

setting a target image on a first surface;

concerning N (N is an integer larger than K) local regions respectivepositions of which can be controlled on the first surface and which canbe divided into K (K is an integer of not less than 2) groups variablesabout states of which can be controlled group by group, determining Nfirst values of the positions and N1 (N1 is an integer not more than Nand larger than K) values of the variables of the local regions,depending upon an error between a first image obtained by arranging theN local regions on the first surface and the target image;

dividing the N local regions into the K groups depending upon the N1values of the variables; and

determining common second values as values of the variables of the localregions in the K groups.

A ninth aspect provides an illumination method for illuminating anillumination target surface with light from a light source, theillumination method comprising:

forming a light quantity distribution of the light from the light sourcebased on the target image on the first surface, using the image formingmethod of the eighth aspect; and

guiding light from the first surface via a condenser optical system tothe illumination target surface.

A tenth aspect provides an exposure method for illuminating a patternwith exposure light and implementing exposure of a substrate with theexposure light via the pattern and the projection optical system,

wherein the pattern is illuminated with the exposure light by theillumination method of the ninth aspect.

An eleventh aspect provides a device manufacturing method comprising:

forming a pattern of a photosensitive layer on the substrate, using theexposure method of the tenth aspect; and

processing the substrate on which the pattern has been formed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a drawing schematically showing a configuration of an exposureapparatus according to an embodiment.

FIG. 2 is a drawing for illustrating a configuration and action of aspatial light modulator.

FIG. 3 is a partial perspective view of major part of the spatial lightmodulator.

FIG. 4 is a drawing showing linear development of an optical path from alens array to an entrance plane of a micro fly's eye lens.

FIG. 5 is a drawing showing regions and polarization states ofrespective beams incident to a diffractive optical element.

FIG. 6 is a drawing showing regions and polarization states ofrespective beams incident to the spatial light modulator.

FIG. 7 is a drawing showing an octupolar pupil intensity distributionobtained in a case where the diffractive optical element and apolarization conversion unit are retracted from the optical path.

FIG. 8 is a perspective view schematically showing a characteristicsurface shape of a polarization conversion member in the polarizationconversion unit.

FIG. 9 is a drawing showing an octupolar pupil intensity distributionobtained in a case where the diffractive optical element and thepolarization conversion unit are placed in the optical path.

FIG. 10 is a drawing showing a state in which another diffractiveoptical element is placed in the optical path.

FIG. 11 is a drawing showing an octupolar pupil intensity distributionobtained in the state of FIG. 10.

FIG. 12 is a drawing showing a state in which the diffractive opticalelement is placed so as to act only on a part of a propagating beam.

FIG. 13 is a drawing showing an octupolar pupil intensity distributionobtained in the state of FIG. 12.

FIG. 14 is a drawing showing an octupolar pupil intensity distributionobtained in a case where in the configuration of FIG. 4 the diffractiveoptical element provides a divergence angle along one plane.

FIG. 15 is a drawing showing an octupolar pupil intensity distributionobtained in a case where in the configuration of FIG. 10 the diffractiveoptical element provides divergence angles along one plane.

FIG. 16 is a drawing showing an octupolar pupil intensity distributionobtained in a case where in the configuration of FIG. 12 the diffractiveoptical element provides a divergence angle along one plane.

FIG. 17 is a drawing showing an octupolar pupil intensity distributionconsisting of outside surface illuminants in a quadrupolar pattern andin a radial polarization state and inside surface illuminants in aquadrupolar pattern and in a circumferential polarization state.

FIG. 18 is a drawing showing an example in which the same pupilintensity distribution as in FIG. 9 is formed by use of three half waveplates.

FIG. 19 is a drawing schematically showing a situation in which a pupilintensity distribution with a desired beam profile is formed by actionof a divergence angle providing member.

FIG. 20 is a drawing showing a major configuration of an example inwhich an entrance optical axis and an exit optical axis are arranged tomake an angle smaller than 45° with an array surface of the spatiallight modulator.

FIG. 21 is a drawing showing a major configuration of an example inwhich the diffractive optical element is arranged on the illuminationtarget surface side of the spatial light modulator.

FIG. 22A, FIG. 22B, and FIG. 22C are drawings showing an example inwhich a light intensity distribution of a beam incident to a polarizingmember is made inhomogeneous.

FIG. 23 is a flowchart showing manufacturing steps of semiconductordevices.

FIG. 24 is a flowchart showing manufacturing steps of a liquid crystaldevice such as a liquid crystal display device.

FIG. 25 is a drawing showing a schematic configuration of an exposureapparatus according to an example of a second embodiment.

FIG. 26A is an enlarged perspective view showing a part of an array ofmirror elements of the spatial light modulator in FIG. 25, and FIG. 26Ba drawing showing an example of a light quantity distribution on anentrance plane (illumination pupil plane) in FIG. 25.

FIG. 27 is a drawing showing arrangement of three sets of diffractiveoptical element groups in FIG. 25.

FIG. 28A is a drawing showing an example of dot patterns formed on theentrance plane (illumination pupil plane) by reflections from aplurality of mirror elements of the spatial light modulator, and FIG.28B a drawing showing another example of dot patterns.

FIG. 29 is a flowchart showing an example of an operation of performingexposure with the pupil shape being set to a target shape.

FIG. 30A is a drawing showing an example of a light quantitydistribution formed on the entrance plane (illumination pupil plane),with relaxation of a condition about the diameters of the dot patternsformed by reflections from the array of mirror elements, and FIG. 30B adrawing showing an example of a light quantity distribution formed onthe entrance plane (illumination pupil plane) with clustering of the dotpatterns in FIG. 30A into three groups.

FIG. 31A is a drawing showing an example of a distribution of diametersd of dot patterns from N mirror elements, which is obtained withrelaxation of the condition about the diameters of the dot patterns,FIG. 31B a drawing showing a state of clustering of the diameterdistribution of the dot patterns in FIG. 31A into three groups, and FIG.31C a drawing showing a state in which the diameters of dot patterns inthe three groups in FIG. 31B are set to the same values.

FIG. 32 is a flowchart showing an example of manufacturing steps ofelectronic devices.

DESCRIPTION OF EMBODIMENTS

Embodiments will be described below based on the accompanying drawings.FIG. 1 is a drawing schematically showing a configuration of an exposureapparatus according to an embodiment. In FIG. 1, the Z-axis is set alonga direction of a normal to a transfer surface (exposure surface) of awafer W being a photosensitive substrate, the Y-axis in a directionparallel to the plane of FIG. 1 in the transfer surface of the wafer W,and the X-axis in a direction perpendicular to the plane of FIG. 1 inthe transfer surface of the wafer W.

Referring to FIG. 1, exposure light (illumination light) is suppliedfrom a light source LS in the exposure apparatus of the presentembodiment. Examples of the light source LS to be used herein include anArF excimer laser light source which supplies light at the wavelength of193 nm, a KrF excimer laser light source which supplies light at thewavelength of 248 nm, and so on. The light emitted in the +Z-directionfrom the light source LS travels through a beam sending unit 1, a lensarray 2 a, and a relay optical system 2 b to impinge on a diffractiveoptical element 3. The diffractive optical element 3 is configured so asto be freely inserted into or retracted from the optical path andfunctions as a divergence angle providing member which provides adivergence angle to an incident beam and emits the beam.

The light having passed through the diffractive optical element 3travels through a reimaging optical system 4 consisting of a front lensunit 4 a and a rear lens unit 4 b, to impinge on a spatial lightmodulator 5. The spatial light modulator 5, as described below, has aplurality of mirror elements arrayed in a predetermined surface andindividually controlled, and a drive unit for individually controllingand driving postures of the plurality of mirror elements, based on acontrol signal from a control system CR. An array surface of the mirrorelements of the spatial light modulator 5 (which will be referred tohereinafter as “array surface of the spatial light modulator”) islocated at a position approximately optically conjugate with thediffractive optical element 3, through the reimaging optical system 4.It is noted herein that the array surface of the spatial light modulatoras the predetermined surface can be regarded as being located in apredetermined space which is a space in an optical path between opticalelements with power adjacent to the array surface. Furthermore, thepredetermined space can also be regarded as an optical path between theoptical element with power adjacent to the array surface on the entranceside of the light with respect to the array surface of the spatial lightmodulator and the optical element with power adjacent to the arraysurface on the exit side of the light with respect to the array surfaceof the spatial light modulator.

The beam sending unit 1 has functions to guide the incident beam fromthe light source LS to the diffractive optical element 3 (and in turn tothe spatial light modulator 5) while converting the incident beam into abeam with a cross section of appropriate size and shape, and to activelycorrect positional variation and angular variation of the lightimpinging on the array surface of the spatial light modulator 5. Thelens array 2 a is composed, for example, of a plurality of lens elementsarranged lengthwise and crosswise and densely along a planeperpendicular to the optical axis AX and implements wavefront divisionof the beam coming from the light source LS through the beam sendingunit 1, into a plurality of beams.

The plurality of beams resulting from the wavefront division by the lensarray 2 a travel through the relay optical system 2 b to be superimposedon the entrance plane of the diffractive optical element 3 and in turntravel through the reimaging optical system 4 to be superimposed on thearray surface of the spatial light modulator 5. Namely, the lens array 2a as wavefront division element and the relay optical system 2 bconstitute a light intensity homogenizing member 2 for improvinghomogeneity of an intensity distribution of the light incident to thediffractive optical element 3. Furthermore, the lens array 2 a, relayoptical system 2 b, and reimaging optical system 4 constitute a lightintensity homogenizing member for making homogeneity in the arraysurface of an intensity distribution of the light incident to the arraysurface of the spatial light modulator 5, higher than homogeneity of anintensity distribution of the light incident to the lens array 2 a, onthe plane where the lens array 2 a is located. Here, focal positions ofthe respective lens elements of the lens array 2 a (or positions ofdivergence origins of the beams resulting from the wavefront division)are approximately coincident with a front focal position of the relayoptical system 2 b, and a rear focal position of the relay opticalsystem 2 b is approximately coincident with the entrance plane of thediffractive optical element 3. Furthermore, the reimaging optical system4 has a function to keep a surface where the diffractive optical element3 is located, optically conjugate with the array surface of the spatiallight modulator 5.

A beam splitter BS is arranged in the optical path between the relayoptical system 2 b and the diffractive optical element 3 and lightextracted from the illumination optical path by the beam splitter BS isincident to a beam monitor BM. The beam monitor BM measures a positionin the array surface of the light incident to the spatial lightmodulator 5, an angle to the array surface of the light incident to thespatial light modulator 5, and a light intensity distribution on thearray surface of the spatial light modulator 5, based on the lightextracted from the illumination optical path. The beam splitter BS to beused can be, for example, an amplitude division type beam splitter or apolarization beam splitter.

The result of the measurement by the beam monitor BM is supplied to thecontrol system CR. The control system CR controls the beam sending unit1 and the spatial light modulator 5, based on the output from the beammonitor BM. The beam monitor BM may be provided with a first imagingunit having a photoelectric conversion surface arranged at a positionoptically conjugate with the array surface of the spatial lightmodulator 5 (a position being approximately in an optical Fouriertransform relation with the lens array 2 a), for measuring the positionof incidence and the light intensity distribution of the light on thearray surface of the spatial light modulator 5 and with a second imagingunit having a photoelectric conversion surface arranged at a positionbeing approximately in an optical Fourier transform relation with thearray surface of the spatial light modulator 5 (a position beingapproximately optically conjugate with the lens array 2 a), formeasuring the angle of incidence of light on the array surface of thelight incident to the spatial light modulator 5. The internalconfiguration of the beam monitor BM is disclosed, for example, in U.S.Pat. Published Application No. 2011/0069305.

A half wave plate 6 is provided in a configuration wherein it is freelyinserted into or retracted from a partial optical path of theillumination optical path (or movable in the Y-directions in FIG. 1) ata position immediately in front of the diffractive optical element 3.The half wave plate 6 functions as a polarizing member for changing apolarization state of a partial beam of a propagating beam propagatingin the illumination optical path. The configuration and action of thespatial light modulator 5 will be described later. Furthermore, thecooperative action of the diffractive optical element 3 as divergenceangle providing member and the half wave plate 6 as polarizing memberwith the spatial light modulator 5 will be described later.

The light emitted into the +Y-direction from the spatial light modulator5 travels through a relay optical system 7 to impinge on a micro fly'seye lens (or on a fly's eye lens) 8A. The relay optical system 7 has itsfront focal position located in the vicinity of the array surface of thespatial light modulator 5 and its rear focal position located in thevicinity of an entrance plane of the micro fly's eye lens 8A, and setsthe array surface of the spatial light modulator 5 and the entranceplane of the micro fly's eye lens 8A in an optical Fourier transformrelation. Therefore, the light having traveled via the spatial lightmodulator 5, as described below, variably forms a light intensitydistribution according to the postures of the mirror elements on theentrance plane of the micro fly's eye lens 8A.

A polarization conversion unit 9 configured so as to be freely insertedinto or retracted from the illumination optical path is provided at aposition immediately in front of the micro fly's eye lens 8A. Thepolarization conversion unit 9 has a function to convertlinearly-polarized incident light with a polarization direction along apredetermined direction into emergent light in a circumferentialpolarization state or into emergent light in a radial polarizationstate. The configuration and action of the polarization conversion unit9 will be described later.

The micro fly's eye lens 8A is, for example, an optical elementconsisting of a large number of microscopic lenses with a positiverefracting power arrayed lengthwise and crosswise and densely and isconstructed by subjecting a plane-parallel plate to an etching processto form a microscopic lens group. In the micro fly's eye lens, differentfrom a fly's eye lens consisting of mutually isolated lens elements, thelarge number of microscopic lenses (microscopic refractive faces) areintegrally formed without being isolated from each other. However, themicro fly's eye lens is an optical integrator of the same wavefrontdivision type as the fly's eye lens in the sense that the lens elementsare arranged lengthwise and crosswise.

The rectangular microscopic refractive faces as unit wavefront divisionfaces in the micro fly's eye lens 8A are of a rectangular shape similarto a shape of an illumination field to be formed on the mask M (and inturn to a shape of an exposure region to be formed on the wafer W). Itis noted that, for example, a cylindrical micro fly's eye lens can alsobe used as the micro fly's eye lens 8A. The configuration and action ofthe cylindrical micro fly's eye lens are disclosed, for example, in U.S.Pat. No. 6,913,373.

The beam incident to the micro fly's eye lens 8A is two-dimensionallydivided by the large number of microscopic lenses and a secondary lightsource with much the same light intensity distribution as a lightintensity distribution formed on the entrance plane (which is asubstantial surface illuminant consisting of a large number of smalllight sources: pupil intensity distribution) is formed on its rear focalplane or on an illumination pupil in the vicinity thereof. Light fromthe secondary light source formed on the illumination pupil immediatelybehind the micro fly's eye lens 8A travels through a condenser opticalsystem 10A to illuminate a mask blind 11A in a superimposed manner. Itis noted herein that a front focal position of the condenser opticalsystem 10A may be located at the position of the secondary light sourceformed immediately behind the micro fly's eye lens 8A and a rear focalposition of the condenser optical system 10A may be set at a settingplane of the mask blind 11A.

In this way, a rectangular illumination field depending on the shape andfocal distance of the entrance faces (wavefront division faces) of therectangular microscopic refractive faces of the micro fly's eye lens 8Ais formed on the mask blind 11A as illumination field stop. Anillumination aperture stop with an aperture (light transmitting portion)of a shape corresponding to the secondary light source may be arrangedat or near the rear focal plane of the micro fly's eye lens 8A, i.e., ata position approximately optically conjugate with an entrance pupilplane of a below-described projection optical system PL.

A beam passing through the rectangular aperture (light transmittingportion) of the mask blind 11A is subject to focusing action of animaging optical system 12A and is reflected into the −Z-direction by anoptical path bending mirror MR1 arranged in the optical path of theimaging optical system 12A, thereafter to illuminate the mask M with apredetermined pattern thereon in a superimposed manner. Namely, theimaging optical system 12A keeps the rectangular aperture of the maskblind 11A optically conjugate with the mask M and forms an image of therectangular aperture of the mask blind 11A on the mask M.

A beam transmitted by the mask M held on a mask stage MS travels throughthe projection optical system PL to form an image of the mask pattern onthe wafer (photosensitive substrate) W held on a wafer stage WS. In thismanner, one-shot exposure or scanning exposure is performed whiletwo-dimensionally driving and controlling the wafer stage WS in a plane(XY plane) perpendicular to the optical axis AX of the projectionoptical system PL and, in turn, two-dimensionally driving andcontrolling the wafer W, whereby each of exposure regions on the wafer Wis sequentially exposed with the pattern on the mask M.

The exposure apparatus of the present embodiment is provided with afirst pupil intensity distribution measuring unit DTr for measuring apupil intensity distribution on an exit pupil plane of the illuminationoptical system, based on the light having traveled via the illuminationoptical system (1 to 12A), a second pupil intensity distributionmeasuring unit DTw for measuring a pupil intensity distribution on apupil plane of the projection optical system PL (exit pupil plane of theprojection optical system PL), based on light having traveled via theprojection optical system PL, and the control system CR for controllingthe spatial light modulator 5, based on at least one of the measurementresults by the first and second pupil intensity distribution measuringunits DTr, DTw, and for totally controlling the operation of theexposure apparatus.

The first pupil intensity distribution measuring unit DTr is provided,for example, with an imaging unit having a photoelectric conversionsurface arranged at a position optically conjugate with the exit pupilposition of the illumination optical system and measures the pupilintensity distribution about points on the illumination target surfaceby the illumination optical system (the pupil intensity distributionformed at the exit pupil position of the illumination optical system bylight beams impinging on the respective points). Furthermore, the secondpupil intensity distribution measuring unit DTw is provided, forexample, with an imaging unit having a photoelectric conversion surfacearranged at a position optically conjugate with the exit pupil positionof the projection optical system PL and measures the pupil intensitydistribution about points on the image plane of the projection opticalsystem PL (the pupil intensity distribution formed at the exit pupilposition of the projection optical system PL by light beams impinging onthe respective points).

For the detailed configuration and action of the first and second pupilintensity distribution measuring units DTr, DTw, reference can be made,for example, to the specification of U.S. Pat. Published Application No.2008/0030707. Furthermore, for the pupil intensity distributionmeasuring units, reference can also be made to the disclosure of U.S.Pat. Published Application No. 2010/0020302.

In the present embodiment, the mask M arranged on the illuminationtarget surface of the illumination optical system (and in turn the waferW) is illuminated by Kohler illumination, using as a light source thesecondary light source formed by the micro fly's eye lens 8A. For thisreason, the position where the secondary light source is formed isoptically conjugate with the position of the aperture stop AS of theprojection optical system PL and the plane where the secondary lightsource is formed can be called an illumination pupil plane of theillumination optical system. Furthermore, an image of this forming planeof the secondary light source can be called an exit pupil plane of theillumination optical system. Typically, the illumination target surface(the surface where the mask M is located, or the surface where the waferW is located in the case where the illumination optical system isconsidered as including the projection optical system PL) is an opticalFourier transform surface for the illumination pupil plane. The pupilintensity distribution is a light intensity distribution (luminancedistribution) on the illumination pupil plane of the illuminationoptical system or on a plane optically conjugate with the illuminationpupil plane.

When the number of wavefront divisions by the micro fly's eye lens 8A isrelatively large, a high correlation is demonstrated between a globallight intensity distribution formed on the entrance plane of the microfly's eye lens 8A and a global light intensity distribution (pupilintensity distribution) of the entire secondary light source. For thisreason, the entrance plane of the micro fly's eye lens 8A and planesoptically conjugate with the entrance plane can also be calledillumination pupil planes and light intensity distributions on theseplanes can also be referred to as pupil intensity distributions. In theconfiguration of FIG. 1, the relay optical system 7 and the micro fly'seye lens 8A constitute a means for forming the pupil intensitydistribution on the illumination pupil immediately behind the microfly's eye lens 8A, based on the beam having traveled via the spatiallight modulator 5.

Next, the configuration and action of the spatial light modulator 5 willbe described specifically. The spatial light modulator 5 is provided, asshown in FIG. 2, with a plurality of mirror elements 5 a arrayed in apredetermined surface, a base 5 b holding the plurality of mirrorelements 5 a, and a drive unit 5 c for individually controlling anddriving postures of the mirror elements 5 a through a cable (not shown)connected to the base 5 b. FIG. 2 shows the optical path from thespatial light modulator 5 to the entrance plane 8 a of the micro fly'seye lens 8A, without illustration of the polarization conversion unit 9.

In the spatial light modulator 5, the postures of the mirror elements 5a each are changed by action of the drive unit 5 c operating based oninstructions from the control system CR, whereby each of the mirrorelements 5 a is set in a predetermined orientation. The spatial lightmodulator 5 is provided, as shown in FIG. 3, with the plurality ofmicroscopic mirror elements 5 a arrayed two-dimensionally and variablyprovides incident light with spatial modulation depending on itsposition of incidence and emits the modulated light. For simplicity ofthe description and illustration, FIGS. 2 and 3 show the configurationexample wherein the spatial light modulator 5 has the mirror elements 5a as many as 4×4=16 elements, but in fact it has the mirror elements 5 afar more than the sixteen mirror elements. For example, the spatiallight modulator 5 may have the mirror elements 5 a as many as about4,000 to 10,000 mirror elements.

Referring to FIG. 2, of a ray group incident to the spatial lightmodulator 5, a ray L1 impinges on a mirror element SEa out of theplurality of mirror elements 5 a and a ray L2 on a mirror element SEbdifferent from the mirror element SEa. Similarly, a ray L3 impinges on amirror element SEc different from the mirror elements SEa, SEb and a rayL4 on a mirror element SEd different from the mirror elements SEa-SEc.The mirror elements SEa-SEd provide the respective rays L1-L4 withrespective spatial modulations set depending on their positions.

The spatial light modulator 5 is configured so that in a standard statein which the reflective faces of all the mirror elements 5 a are setalong one plane, a ray incident along a direction parallel to theoptical axis AX of the reimaging optical system 4 is reflected on thespatial light modulator 5 and thereafter travels in a direction parallelto the optical axis AX of the relay optical system 7. Furthermore, asdescribed above, the array surface of the mirror elements 5 a of thespatial light modulator 5 and the entrance plane 8 a of the micro fly'seye lens 8A are located in the optical Fourier transform relationthrough the relay optical system 7.

Therefore, the rays reflected by the mirror elements SEa-SEd of thespatial light modulator 5 while being provided with a predeterminedangle distribution form predetermined light intensity distributions SP1to SP4 on the entrance plane 8 a of the micro fly's eye lens 8A. Namely,while the relay optical system 7 is arranged with its front focalposition located at the array surface of the spatial light modulator 5and its rear focal position located at the entrance plane 8 a of themicro fly's eye lens 8A, it converts angles provided to the respectiveemergent rays by the mirror elements SEa-SEd of the spatial lightmodulator 5, to positions on the entrance plane 8 a being the far field(Fraunhofer diffraction region) of the spatial light modulator 5. Inthis manner, the light intensity distribution (pupil intensitydistribution) of the secondary light source formed by the micro fly'seye lens 8A becomes a distribution corresponding to the light intensitydistribution formed on the entrance plane 8 a of the micro fly's eyelens 8A by the spatial light modulator 5 and the relay optical system 7.It is noted that the front focal position of the relay optical system 7may be located at a position off the array surface of the spatial lightmodulator 5 as long as it resides in the aforementioned predeterminedspace. Furthermore, the rear focal position of the relay optical system7 may be located in the vicinity of the entrance plane 8 a without needfor being located exactly at the position of the entrance plane 8 a ofthe micro fly's eye lens 8A.

The spatial light modulator 5, as shown in FIG. 3, is a movablemulti-mirror including the mirror elements 5 a which are a large numberof microscopic reflective elements arrayed regularly andtwo-dimensionally along one plane with their planar reflective facesfacing up. Each mirror element 5 a is movable and an inclination of itsreflective face, which is defined by an inclination angle and aninclination direction of the reflective face, is independentlycontrolled by action of the drive unit 5 c operating based on a controlsignal from the control system CR. Each mirror element 5 a can becontinuously or discretely rotated by a desired rotation angle about twodirections parallel to its reflective face and perpendicular to eachother, as rotation axes. Namely, the inclination of the reflecting faceof each mirror element 5 a can be two-dimensionally controlled.

In the case where the reflecting face of each mirror element 5 a isdiscretely rotated, it is preferable to control it by switching therotation angle in a plurality of states (e.g., . . . , −2.5°, −2.0°, . .. 0°, +0.5° . . . +2.5°, . . . ). FIG. 3 shows the mirror elements 5 awith their contour of square shape, but the contour shape of the mirrorelements 5 a is not limited to the square shape. However, in view oflight utilization efficiency, it is possible to adopt a shape allowingan array with gaps between the mirror elements 5 a as small as possible(shape permitting the closest packing). In addition, in view of lightutilization efficiency, the gaps between two adjacent mirror elements 5a can be kept down to the necessary minimum.

In the present embodiment, the spatial light modulator 5 to be used is,for example, the spatial light modulator in which each of theorientations of the plurality of mirror elements 5 a arrayedtwo-dimensionally is continuously changed. Such a spatial lightmodulator to be used herein can be one of the spatial light modulatorsdisclosed, for example, in European Patent Application Publication EP779530, U.S. Pat. No. 5,867,302, U.S. Pat. No. 6,480,320, U.S. Pat. No.6,600,591, U.S. Pat. No. 6,733,144, U.S. Pat. No. 6,900,915, U.S. Pat.No. 7,095,546, U.S. Pat. No. 7,296,726, U.S. Pat. No. 7,424,330, U.S.Pat. No. 7,567,375, U.S. Pat. Published Application No. 2008/0309901,U.S. Pat. Published Application No. 2011/0181852, U.S. Pat. PublishedApplication No. 2011/188017, and Japanese Patent Application Laid-OpenPublication No. 2006-113437. It is noted that the orientations of themirror elements 5 a arrayed two-dimensionally may be controlled so as tohave a plurality of discrete stages.

In the spatial light modulator 5, the postures of the mirror elements 5a each are changed by action of the drive unit 5 c operating inaccordance with a control signal from the control system CR, wherebyeach of the mirror elements 5 a is set in a predetermined orientation.Rays reflected at respective predetermined angles by the mirror elements5 a of the spatial light modulator 5 form a desired pupil intensitydistribution on the illumination pupil of the entrance plane 8 a of themicro fly's eye lens 8A and, in turn, on the illumination pupilimmediately behind the micro fly's eye lens 8A. Furthermore, a desiredpupil intensity distribution is also formed at positions of otherillumination pupils optically conjugate with the illumination pupilimmediately behind the micro fly's eye lens 8A, i.e., at the pupilposition of the imaging optical system 12A and at the pupil position ofthe projection optical system PL (the position where the aperture stopAS is located).

As described above, the spatial light modulator 5 variably forms thepupil intensity distribution on the illumination pupil immediatelybehind the micro fly's eye lens 8A. The relay optical system 7constitutes a distribution forming optical system for imaging the farfield pattern formed in the far field by the mirror elements 5 a of thespatial light modulator 5, on the illumination pupil of the entranceplane 8 a of the micro fly's eye lens 8A. This distribution formingoptical system converts a distribution of angular directions of emergentbeams from the spatial light modulator 5, into a position distributionon the cross section of the emergent beam from the distribution formingoptical system.

FIG. 4 is a drawing showing linear development of the optical path fromthe lens array 2 a to the entrance plane 8 a of the micro fly's eye lens8A. FIG. 4 shows the spatial light modulator 5 as a transmission typespatial light modulator and x-axis, y-axis, and z-axis are set in adirection perpendicular to the plane of the drawing, in a direction ofthe optical axis AX extending horizontally on the plane of the drawing,and in a vertical direction on the plane of the drawing, respectively.In FIG. 4, the half wave plate 6 is arranged at the position immediatelyin front of the diffractive optical element 3, i.e., at the positionapproximately optically conjugate with the array surface of the spatiallight modulator 5, so as to act on a beam propagating in the opticalpath in the +z-direction from the xy plane including the optical axisAX. The half wave plane 6 is arranged so that its entrance plane andexit plane are perpendicular to the optical axis AX.

It is assumed below, for easier understanding of the description, that aparallel beam having a rectangular cross section with light intensityhomogenized by action of the light intensity homogenizing member 2 isincident to the diffractive optical element 3 and that the light havingtraveled via the light intensity homogenizing member 2 is linearlypolarized light polarized in the z-direction (which will be referred tohereinafter as “z-directionally linearly polarized light”). The halfwave plate 6 is arranged so that the orientation of its optic axis isset in a direction at 45° to the x-direction and the z-direction in thexz plane, so as to, with incidence of z-directionally linearly polarizedlight thereto, emit x-directionally linearly polarized light with thepolarization direction along the x-direction resulting from +90°rotation (90° clockwise rotation on the plane of FIG. 5) of thez-direction.

Therefore, as shown in FIG. 5, a first beam F11 incident to the regionin the −z-direction from the xy plane including the optical axis AX, ofthe beam F1 incident to the diffractive optical element 3 (parallel beamF1 of z-directionally linearly polarized light having the rectangularcross section centered on the optical axis AX) is not subject to theaction of the half wave plate 6 and thus is emergent as z-directionallylinearly polarized light. On the other hand, a second beam F12 incidentto the region in the +z-direction from the xy plane including theoptical axis AX is subject to the action of the half wave plate 6,thereby to turn into x-directionally linearly polarized light.

The diffractive optical element 3 has such a characteristic that when aparallel beam is incident thereto, it converts the parallel beam into adivergent beam with a predetermined divergence angle and emits thedivergent beam. If the parallel beam is not incident to the diffractiveoptical element 3 in the embodiment, the incident beam with an angledistribution is further provided with a divergence angle. Namely, thediffractive optical element 3 provides a required divergence angle tothe incident beams F11 and F12 and emits them. Specifically, thediffractive optical element 3 provides the same divergence angle acrossall azimuth directions to the incident beams F11 and F12.

The first beam F11 and the second beam F12 provided with the divergenceangle travel through the relay optical system 7 to impinge on thespatial light modulator 5. Namely, as shown in FIG. 6, the first beamF11 impinges on a first region R11 in the +z-direction from the xy planeincluding the optical axis AX, of an effective reflective region R1 inthe array surface of the spatial light modulator 5. The second beam F12impinges on a second region R12 in the −z-direction from the xy planeincluding the optical axis AX, of the effective reflective region R1.

Now, Let us consider a case where the diffractive optical element 3 andthe polarization conversion unit 9 are retracted from the optical path;as shown in FIG. 7, the drive unit 5 c of the spatial light modulator 5controls each of the postures of the mirror elements 5 a belonging to afirst mirror element group S11 so that light having traveled via thefirst mirror element group S11 located in the first region R11 is guidedto four outside pupil regions R21 a, R21 b, R21 c, and R21 d on theentrance plane 8 a of the micro fly's eye lens 8A. A pair of pupilregions R21 a, R21 b are, for example, regions arranged with a space inthe x-direction on both sides of the optical axis AX. A pair of pupilregions R21 c, R21 d are, for example, regions arranged with a space inthe z-direction on both sides of the optical axis AX.

The drive unit 5 c controls each of the postures of the mirror elements5 a belonging to a second mirror element group S12 so that light havingtraveled via the second mirror element group S12 located in the secondregion R12 is guided to four inside pupil regions R22 a, R22 b, R22 c,and R22 d on the entrance plane 8 a. A pair of pupil regions R22 a, R22b are, for example, regions arranged with a space in a direction at 45°to the +x-direction and the −z-direction on both sides of the opticalaxis AX. A pair of pupil regions R22 c, R22 d are, for example, regionsarranged with a space in a direction at 45° to the +x-direction and the+z-direction on both sides of the optical axis AX.

In this manner, when the diffractive optical element 3 and thepolarization conversion unit 9 are retracted from the optical path, thespatial light modulator 5 forms an octupolar light intensitydistribution 21 p consisting of eight substantial surface illuminantsP21 a, P21 b; P21 c, P21 d; P22 a, P22 b; P22 c, P22 d, on theillumination pupil of the entrance plane 8 a of the micro fly's eye lens8A. Namely, the first beam F11 travels via the first mirror, elementgroup S11 of the spatial light modulator 5 to form the surfaceilluminants P21 a-P21 d covering the pupil regions R21 a-R21 d. Thelight forming the surface illuminants P21 a-P21 d is z-directionallylinearly polarized light because it does not pass through the half waveplate 6.

The second beam F12 travels via the second mirror element group S12 ofthe spatial light modulator 5 to form the surface illuminants P22 a-P22d covering the pupil regions R22 a-R22 d. The light forming the surfaceilluminants P22 a-P22 d is x-directionally linearly polarized lightbecause it passes through the half wave plate 6. Furthermore, anoctupolar pupil intensity distribution corresponding to the lightintensity distribution 21 p is also formed at the position of theillumination pupil immediately behind the micro fly's eye lens 8A, atthe pupil position of the imaging optical system 12A, and at the pupilposition of the projection optical system PL.

The control system CR can be constructed, for example, of a so-calledworkstation (or a microcomputer) or the like composed of a CPU (centralprocessing unit), a ROM (read only memory), a RAM (random accessmemory), and so on and can totally control the entire apparatus.Furthermore, the control system CR may have external equipment, forexample, including a storage unit consisting of a hard disc, inputdevices including a keyboard and a pointing device such as a mouse, adisplay device such as a CRT display (or a liquid crystal display), anda drive unit for an information storage medium such as CD (compactdisc), DVD (digital versatile disc), MO (magneto-optical disc), or FD(flexible disc).

The storage unit may store information about pupil intensitydistributions (illumination light source shapes) with an imaged state ofa projection image projected on the wafer W by the projection opticalsystem PL being optimal (e.g., with aberration or the line width fallingwithin a tolerable range), control information on the illuminationoptical system corresponding thereto and, particularly, on the mirrorelements of the spatial light modulator 5, and so on. An informationstorage medium storing programs for executing below-described setting ofpupil intensity distribution (CD-ROM in the below description forconvenience) and the like may be set in the drive unit. These programsmay be installed in the storage unit. The control system CR reads theseprograms onto the memory as occasion demands.

The control system CR can control the spatial light modulator 5, forexample, by the following procedure. The pupil intensity distributioncan be expressed, for example, in a format in which the pupil plane isdivided into a plurality of grid-like sections and the distribution isexpressed as numerical values using light intensities and polarizationstates of the respective sections (bitmap format in a broad sense). Whenit is assumed herein that the number of mirror elements of the spatiallight modulator 5 is N and the number of sections resulting from thedivision of the pupil intensity distribution is M, the pupil intensitydistribution (secondary light source) is formed (or set) by guiding Nrays reflected by the individual mirror elements, in appropriatecombinations to the M sections, or, by appropriately superimposing the Nrays on M bright spots composed of the M sections.

First, the control unit CR reads information about the pupil intensitydistribution 21 p as a target from the storage unit. Next, it calculateshow many rays are needed for forming an intensity distribution in eachof polarization states, from the information about the pupil intensitydistribution 21 p thus read out. Then the control unit CR virtuallydivides the plurality of mirror elements 5 a of the spatial lightmodulator 5 into two mirror element groups S11 and S12 each consistingof a necessary number of mirror elements, and sets the partial regionsR11 and R12 where the respective mirror element groups S11 and S12 arelocated.

The control unit CR drives the mirror elements 5 a in the first mirrorelement group S11 located in the partial region R11 of the spatial lightmodulator 5 to implement such a setting that light from the first mirrorelement group S11 travels toward the pupil regions R21 a-R21 d coveredby the surface illuminants P21 a-P21 d. Similarly, the control unit CRdrives the mirror elements 5 a in the second mirror element group S12located in the partial region R12 of the spatial light modulator 5 toimplement such a setting that light from the second mirror element groupS12 travels toward the pupil regions R22 a-R22 d covered by the surfaceilluminants P22 a-P22 d. Furthermore, the control unit CR controls theposition in the Y-direction of the half wave plate 6 so that the beamtraveling toward the partial region R12 of the spatial light modulator 5passes through the half wave plate 6 as polarizing member (or so thatthe edge in the X-direction of the half wave plate 6 is located at aboundary between the partial regions R11 and R12).

FIG. 8 is a perspective view schematically showing a characteristicsurface shape of a polarization conversion member in the polarizationconversion unit. The polarization conversion unit 9, as shown in FIG. 4,has a correction member 91 and a polarization conversion member 92 inorder from the light entrance side (light source side). The polarizationconversion member 92 is made of a crystal material being an opticalmaterial with optical rotatory power, e.g., rock crystal and has a formin which the thickness continuously varies along the circumferentialdirection of a circle centered on the optical axis AX. As an example, anentrance-side surface 92 a of the polarization conversion member 92 isformed in a surface shape with a linear level difference as shown inFIG. 8 and an exit-side (mask-side) surface 92 b is formed in a planarshape.

Specifically, the entrance-side surface 92 a of the polarizationconversion member 92 has the linear level difference extending acrossthe entire surface 92 a along the z-direction while passing the opticalaxis AX. A semicircular face 92 aa on the +x-directional side withrespect to this level difference is formed so that the thicknesslinearly increases from the +z-directional side to the −z-directionalside along the circumferential direction of a semicircle centered on theoptical axis AX. On the other hand, a semicircular face 92 ab on the−x-directional side with respect to the level difference is formed sothat the thickness linearly increases from the −z-directional side tothe +z-directional side along the circumferential direction of asemicircle centered on the optical axis AX.

When we now consider a circular column (cylindrical) coordinate systemwherein the xz plane perpendicular to the optical axis AX is set as areference plane and the origin is set at the position of the opticalaxis AX on the reference plane, the semicircular face 92 aa on the+x-directional side with respect to the level difference and thesemicircular face 92 ab on the −x-directional side with respect to thelevel difference have the curved shape in which the thickness in theoptical-axis direction (y-direction) varies depending only on deviationsbeing azimuth angles about the optical axis AX. The correction member 91is arranged next on the entrance side to the polarization conversionmember 92 and is made of an optical material having the same refractiveindex as the polarization conversion member 92, i.e., rock crystal.

The correction member 91 has a required surface shape for functioning asa compensator to compensate for light deflection action (change intraveling direction of light) by the polarization conversion member 92.Specifically, an entrance-side face of the correction member 91 isformed in a planar shape and an exit-side face has a surface shapecomplementary to the surface shape of the entrance-side surface 92 a ofthe polarization conversion member 92. The correction member 91 isarranged so that its crystallographic optic axis becomes parallel orperpendicular to the polarization direction of incident light, so as notto change the polarization state of passing light. The polarizationconversion member 92 is set so that its crystallographic optic axisbecomes approximately coincident with the optical axis AX (i.e.,approximately coincident with the y-direction being the travelingdirection of incident light), in order to change the polarization stateof incident light.

In the polarization conversion unit 9, the thickness distribution of thepolarization conversion member 92 is set so that, for example, when abeam of z-directionally linearly polarized light with an annular crosssection is incident thereto, an annular beam is formed in a continuouscircumferential polarization state immediately behind the polarizationconversion member 92. Namely, the polarization conversion member 92 isformed so as to convert the z-directionally linearly polarized lightimpinging on an arbitrary point on its entrance surface 92 a, intolinearly polarized light with the polarization direction along a tangentdirection to a circle centered on the optical axis AX and passing thepoint of incidence.

As a result, for example, when a beam of x-directionally linearlypolarized light with an annular cross section is incident to thepolarization conversion unit 9, an annular beam is formed in acontinuous radial polarization state immediately behind the polarizationconversion member 92. Namely, the polarization conversion member 92 isformed so as to convert x-directionally linearly polarized lightimpinging on an arbitrary point on its entrance surface 92 a, intolinearly polarized light with the polarization direction along a radialdirection of a circle centered on the optical axis AX and passing thepoint of incidence. It is noted that the polarization conversion member92 may have a form in which the thickness intermittently (stepwise)varies along the circumferential direction of the circle entered on theoptical axis AX. The polarization conversion member 92 of this kind tobe used can be, for example, the polarization conversion memberdisclosed in U.S. Pat. Published Application No. 2009/0316132.

Therefore, when the diffractive optical element 3 and the polarizationconversion unit 9 are placed in the optical path, an octupolar lightintensity distribution 22 p consisting of light intensity distributionsP31 a, P31 b, P31 c, and P31 d in a quadrupolar pattern and in acircumferential polarization state and light intensity distributions P32a, P32 b, P32 c, and P32 d in a quadrupolar pattern and in a radialpolarization state is formed, as shown in FIG. 9, on the illuminationpupil of the entrance plane 8 a of the micro fly's eye lens 8A.Furthermore, an octupolar pupil intensity distribution corresponding tothe light intensity distribution 22 p is also formed at the position ofthe illumination pupil immediately behind the micro fly's eye lens 8A,at the pupil position of the imaging optical system 12A, and at thepupil position of the projection optical system PL.

Regions R31 a, R31 b, R31 c, and R31 d covered by the surfaceilluminants P31 a-P31 d are located at positions corresponding to theregions R21 a-R21 d in FIG. 7 (which are indicated by dashed lines inFIG. 9) and have shapes obtained by similarly enlarging the regions R21a-R21 d depending on the magnitude of the divergence angle provided bythe diffiactive optical element 3. Similarly, regions R32 a, R32 b, R32c, and R32 d covered by the surface illuminants P32 a-P32 d are locatedat positions corresponding to the regions R22 a-R22 d in FIG. 7 (whichare indicated by dashed lines in FIG. 9) and have shapes obtained bysimilarly enlarging the regions R22 a-R22 d depending on the magnitudeof the divergence angle provided by the diffractive optical element 3.

In general, in the case of circumferential polarization illuminationbased on an annular or multi-polar (dipolar, quadrupolar, octupolar,etc.) pupil intensity distribution in a circumferential polarizationstate, light impinging on the wafer W as a final illumination targetsurface is in a polarization state with the principal component ofs-polarized light. Here, the s-polarized light refers to linearlypolarized light with the polarization direction along a direction normalto the plane of incidence (which is polarized light with the electricvector oscillating in the direction normal to the plane of incidence).The plane of incidence is defined as a plane including, with lightarriving at a boundary surface of a medium (illumination target surface:surface of wafer W), a normal to the boundary surface at the arrivalpoint and a direction of incidence of the light. As a result, thecircumferential polarization illumination improves optical performanceof the projection optical system (depth of focus and others) and allowsacquisition of a mask pattern image with high contrast on the wafer(photosensitive substrate).

On the other hand, in the case of radial polarization illumination basedon an annular or multi-polar pupil intensity distribution in a radialpolarization state, light impinging on the wafer W as a finalillumination target surface is in a polarization state with theprincipal component of p-polarized light. Here, the p-polarized light islinearly polarized light with the polarization direction along adirection parallel to the plane of incidence defined as described above(which is polarized light with the electric vector oscillating in thedirection parallel to the plane of incidence). As a result, the radialpolarization illumination keeps low the reflectance of light on a resistapplied to the wafer W and allows acquisition of a good mask patternimage on the wafer (photosensitive substrate).

In the present embodiment, the diffractive optical element 3 isconfigured so as to be interchangeable with another diffractive opticalelement 3 a having a different characteristic. Examples of a method forswitching the diffractive optical elements include the well-known turretmethod, slide method, and so forth. The diffractive optical element 3 a,as shown in FIG. 10, provides mutually different divergence angles tothe incident beams F11 and F12 and emits them. Specifically, thediffractive optical element 3 a provides a smaller divergence angleacross all the azimuth directions to the incident beam F11 than thediffractive optical element 3 does, and the same divergence angle acrossall the azimuth directions to the incident beam F12 as the diffractiveoptical element 3 does.

In other words, the diffractive optical element 3 a has a first region(region of incidence of the beam F11) with a characteristic to convert aparallel beam incident thereto, into a first divergent beam with a firstdivergence angle, and a second region (region of incidence of the beamF12) with a characteristic to convert a parallel beam incident thereto,into a second divergent beam with a second divergence angle larger thanthe first divergence angle. In still another expression, the diffractiveoptical element 3 a provides the divergence angles to the propagatingbeam propagating in the optical path, to generate the beams F11, F12with the different divergence angles and these beams are emitted fromthe diffractive optical element 3 a so as to pass at mutually differentpositions on the surface where the diffractive optical element 3 a isplaced. In yet another expression, the diffractive optical element 3 amakes a distribution on the exit plane of divergence angles from theexit plane with incidence of a parallel beam to the diffractive opticalelement 3 a, different from a distribution on the exit plane ofdivergence angles from the exit plane with incidence of a parallel beamto the diffractive optical element 3.

Therefore, when the diffractive optical element 3 a is arranged in theoptical path instead of the diffractive optical element 3, an octupolarlight intensity distribution 23 p consisting of light intensitydistributions P41 a, P41 b, P41 c, and P41 d in a quadrupolar patternand in a circumferential polarization state and light intensitydistributions P42 a, P42 b, P42 c, and P42 d in a quadrupolar patternand in a radial polarization state is formed, as shown in FIG. 11, onthe illumination pupil of the entrance plane 8 a of the micro fly's eyelens 8A.

Regions R41 a, R41 b, R41 c, and R41 d covered by the surfaceilluminants P41 a-P41 d are located at positions corresponding to theregions R21 a-R21 d in FIG. 7 (which are indicated by dashed lines inFIG. 11) and have shapes obtained by similarly enlarging the regions R21a-R21 d at a relatively small magnification depending on the relativelysmall divergence angle provided by the diffractive optical element 3 a.Similarly, regions R42 a, R42 b, R42 c, and R42 d covered by the surfaceilluminants P42 a-P42 d are located at positions corresponding to theregions R22 a-R22 d in FIG. 7 (which are indicated by dashed lines inFIG. 11) and have shapes obtained by similarly enlarging the regions R22a-R22 d at a relatively large magnification depending on the relativelylarge divergence angle provided by the diffractive optical element 3 a.In the example of FIG. 10, the direction of the change in degree ofprovision of the divergence angles in the diffractive optical element 3a (the z-direction in the drawing) was the same direction as the movingdirection of the half wave plane 6 as polarizing member, but thedirection of the change in degree of provision of the divergence anglesin the diffractive optical element 3 a may be a direction perpendicularto the moving direction of the half wave plate 6.

FIG. 12 is a drawing showing a state in which the diffractive opticalelement 3 is arranged so as to act only on a part of the propagatingbeam. In this case, the diffractive optical element 3 provides therequired divergence angle across all the azimuth directions only to theincident beam F12. In other words, the diffiactive optical element 3provides the divergence angle to the partial beam F12 of the propagatingbeam propagating in the optical path, to generate the beams F11, F12with the different divergence angles.

Therefore, when the diffractive optical element 3 is arranged so as toact only on the beam F12, an octupolar light intensity distribution 24 pconsisting of light intensity distributions P51 a, P51 b, P51 c, and P51d in a quadrupolar pattern and in a circumferential polarization stateand light intensity distributions P52 a, P52 b, P52 c, and P52 d in aquadrupolar pattern and in a radial polarization state is formed, asshown in FIG. 13, on the illumination pupil of the entrance plane 8 a ofthe micro fly's eye lens 8A.

Regions R51 a, R51 b, R51 c, and R51 d covered by the surfaceilluminants P51 a-P51 d are coincident with the regions R21 a-R21 d inFIG. 7. On the other hand, regions R52 a, R52 b, R52 c, and R52 dcovered by the surface illuminants P52 a-P52 d are located at positionscorresponding to the regions R22 a-R22 d in FIG. 7 (which are indicatedby dashed lines in FIG. 13) and have shapes obtained by similarlyenlarging the regions R22 a-R22 d depending on the divergence angleprovided by the diffractive optical element 3.

In the above description, the diffractive optical element 3, 3 aprovides the required divergence angle(s) across all the azimuthdirections to the incident beam, but it is also possible to adopt aconfiguration wherein the diffractive optical element 3, 3 a providesthe divergence angle(s), for example, along the yz plane but does notprovide the divergence angle(s) along the xy plane. Specifically, whenin the configuration of FIG. 4 the diffractive optical element 3provides the divergence angle along the yz plane but does not providethe divergence angle along the xy plane, an octupolar light intensitydistribution 25 p consisting of light intensity distributions P61 a, P61b, P61 c, and P61 d in a quadrupolar pattern and in a circumferentialpolarization state and light intensity distributions P62 a, P62 b, P62c, and P62 d in a quadrupolar pattern and in a radial polarization stateis formed, as shown in FIG. 14, on the illumination pupil of theentrance plane 8 a of the micro fly's eye lens 8A.

Regions R61 a, R61 b, R61 c, and R61 d covered by the surfaceilluminants P61 a-P61 d are located at positions corresponding to theregions R21 a-R21 d in FIG. 7 (which are indicated by dashed lines inFIG. 14) and have shapes obtained by enlarging the regions R21 a-R21 donly in the z-direction depending on the magnitude of the divergenceangle provided by the diffractive optical element 3. Similarly, regionsR62 a, R62 b, R62 c, and R62 d covered by the surface illuminants P62a-P62 d are located at positions corresponding to the regions R22 a-R22d in FIG. 7 (which are indicated by dashed lines in FIG. 14) and haveshapes obtained by enlarging the regions R22 a-R22 d only in thez-direction depending on the magnitude of the divergence angle providedby the diffractive optical element 3.

When in the configuration of FIG. 10 the diffractive optical element 3 aprovides the divergence angles along the yz plane but does not providethe divergence angles along the xy plane, an octupolar light intensitydistribution 26 p consisting of light intensity distributions P71 a, P71b, P71 c, and P71 d in a quadrupolar pattern and in a circumferentialpolarization state and light intensity distributions P72 a, P72 b, P72c, and P72 d in a quadrupolar pattern and in a radial polarization stateis formed, as shown in FIG. 15, on the illumination pupil of theentrance plane 8 a of the micro fly's eye lens 8A.

Regions R71 a, R71 b, R71 c, and R71 d covered by the surfaceilluminants P71 a-P71 d are located at positions corresponding to theregions R21 a-R21 d in FIG. 7 (which are indicated by dashed lines inFIG. 15) and have shapes obtained by enlarging the regions R21 a-R21 dat the relatively small magnification only in the z-direction dependingon the relatively small divergence angle provided by the diffractiveoptical element 3 a. Similarly, regions R72 a, R72 b, R72 c, and R72 dcovered by the surface illuminants P72 a-P72 d are located at positionscorresponding to the regions R22 a-R22 d in FIG. 7 (which are indicatedby dashed lines in FIG. 15) and have shapes obtained by enlarging theregions R22 a-R22 d at the relatively large magnification only in thez-direction depending on the relatively large divergence angle providedby the diffractive optical element 3 a.

When in the configuration of FIG. 12 the diffractive optical element 3provides the divergence angle along the yz plane but does not providethe divergence angle along the xy plane, an octupolar light intensitydistribution 2′7 p consisting of light intensity distributions P81 a,P81 b, P81 c, and P81 d in a quadrupolar pattern and in acircumferential polarization state and light intensity distributions P82a, P82 b, P82 c, and P82 d in a quadrupolar pattern and in a radialpolarization state is formed, as shown in FIG. 16, on the illuminationpupil of the entrance plane 8 a of the micro fly's eye lens 8A.

Regions R81 a, R81 b, R81 c, and R81 d covered by the surfaceilluminants P81 a-P81 d are coincident with the region R21 a-R21 d inFIG. 7. On the other hand, regions R82 a, R82 b, R82 c, and R82 dcovered by the surface illuminants P82 a-P82 d are located at positionscorresponding to the regions R22 a-R22 d in FIG. 7 (which are indicatedby dashed lines in FIG. 16) and have shapes obtained by enlarging theregions R22 a-R22 d only in the z-direction depending on the divergenceangle provided by the diffractive optical element 3.

In the above description, the light intensity distributions 22 p-27 pare formed with the outside quadrupolar surface illuminants in thecircumferential polarization state and with the inside quadrupolarsurface illuminates in the radial polarization state. However, forexample, when the configuration of FIG. 4 is modified so that the lightthrough the light intensity homogenizing member 2 is set to be thex-directionally linearly polarized light or so that the half wave plate6 is arranged so as to act on the beam F11 propagating in the opticalpath in the −z-direction from the xy plane including the optical axisAX, it is feasible to form an octupolar light intensity distribution 28p consisting of light intensity distributions P91 a, P91 b, P91 c, andP91 d in a quadrupolar pattern and in a radial polarization state andlight intensity distributions P92 a, P92 b, P92 c, and P92 d in aquadrupolar pattern and in a circumferential polarization state, asshown in FIG. 17.

Furthermore, although illustration is omitted, for example, theconfiguration of FIG. 10 and the configuration of FIG. 12 can bemodified so that the light through the light intensity homogenizingmember 2 is set to be the x-directionally linearly polarized light or sothat the half wave plate 6 is arranged so as to act on the beam F11propagating in the optical path in the −z-direction from the xy planeincluding the optical axis AX, whereby it is feasible to form anoctupolar light intensity distribution consisting of outside surfaceilluminants in a quadrupolar pattern and in a radial polarization stateand inside surface illuminants in a quadrupolar pattern and in acircumferential polarization state.

In the above description, the polarization conversion unit 9 is used toform the octupolar light intensity distribution 22 p consisting of thelight intensity distributions P31 a-P31 d in the quadrupolar pattern andin the circumferential polarization state and the light intensitydistributions P32 a-P32 d in the quadrupolar pattern and in the radialpolarization state as shown in FIG. 9. However, without the use of thepolarization conversion unit 9, the octupolar light intensitydistribution 22 p can be formed, for example, by using three half waveplates 6, 6 a, and 6 b as shown in FIG. 18.

In the example shown in FIG. 18, the three half wave plates 6, 6 a, and6 b with mutually different polarization conversion characteristics arearranged in juxtaposition at the position immediately in front of thediffractive optical element 3. As an example, the half wave plates 6, 6a, and 6 b are arranged so that quarter beams F21, F22, and F23 of apropagating beam F2 propagating in the optical path are incident to thehalf wave plates 6, 6 a, and 6 b, respectively. Therefore, the restquarter beam F24 of the propagating beam F2 travels without passingthrough any one of the half wave plates 6, 6 a, and 6 b, to reach thediffractive optical element 3.

The half wave plate 6, as described above, has its crystallographicoptic axis set in such a direction that when the z-directionallylinearly polarized light is incident thereto, it emits thex-directionally linearly polarized light with the polarization directionalong the x-direction resulting from +90° rotation (90° clockwiserotation on the plane of FIG. 18) of the z-direction. The half waveplate 6 a has its crystallographic optic axis set in such a directionthat when the z-directionally linearly polarized light is incidentthereto, it emits −45° obliquely linearly polarized light with thepolarization direction along a −45° oblique direction resulting from−45° rotation (45° counterclockwise rotation on the plane of FIG. 18) ofthe z-direction.

The half wave plate 6 b has its crystallographic optic axis set in sucha direction that when the z-directionally linearly polarized light isincident thereto, it emits +45° obliquely linearly polarized light withthe polarization direction along a +45° oblique direction resulting from+45° rotation of the z-direction. In the example shown in FIG. 18, thefirst beam F21 travels through the half wave plate 6 to becomex-directionally linearly polarized light and then travels via a firstmirror element group of the spatial light modulator 5 to form thesurface illuminants P31 c, P31 d covering the pupil regions R31 c, R 31d.

The second beam F22 travels through the half wave plate 6 a to become−45° obliquely linearly polarized light and then travels via a secondmirror element group of the spatial light modulator 5 to form thesurface illuminants P32 a, P32 b covering the pupil regions R32 a, R32b. The third beam F23 travels through the half wave plate 6 b to become+45° obliquely linearly polarized light and then travels via a thirdmirror element group of the spatial light modulator 5 to form surfaceilluminants P32 c, P32 d covering pupil regions R32 c, R32 d.

The fourth beam F24 travels as the z-directionally linearly polarizedlight without being subject to the action of the half wave plates 6, 6a, 6 b and then travels via a fourth mirror element group of the spatiallight modulator 5 to form the surface illuminants P31 a, P31 b coveringthe pupil regions R31 a, R31 b. Similarly, without the use of thepolarization conversion unit 9, it is also possible to form theoctupolar light intensity distributions 23 p-28 p, for example, using apolarizing member consisting of a plurality of polarizing elements suchas the three half wave plates 6, 6 a, and 6 b.

In FIG. 18 the half wave plates 6 and 6 a are adjacent in thex-direction and the half wave plates 6 and 6 b are adjacent in thez-direction, but the arrangement of the three half wave plates 6, 6 a,and 6 b can be modified in various ways. Namely, at least two half waveplates out of the three half wave plates 6, 6 a, and 6 b may be arrangedwith a space between them along the xz plane.

In the above description, the octupolar light intensity distributions 21p-28 p are formed on the entrance plane 8 a of the micro fly's eye lens8A and in turn on the illumination pupil immediately behind the microfly's eye lens 8A. However, without being limited to the octupolarpatterns, it is possible to form other multi-polar (e.g., quadrupolar,hexapolar, or the like) pupil intensity distributions, annular pupilintensity distributions, or the like by the action of the spatial lightmodulator 5. Namely, since the present embodiment is provided with thespatial light modulator 5 having the large number of mirror elements 5 athe postures of which are individually controlled, degrees of freedomare high about change in the contour shape of the pupil intensitydistribution (which is a broad concept embracing the size).

In addition, since the present embodiment is provided with the half waveplate 6 (6 a, 6 b) arranged at the position approximately opticallyconjugate with the array surface of the spatial light modulator 5 andthe polarization conversion unit 9 arranged in the optical pathaccording to needs, degrees of freedom are also high about change inpolarization states of the pupil intensity distribution. Furthermore,since the present embodiment is provided with the diffractive opticalelement 3 (3 a) as the divergence angle providing member arranged at theposition approximately optically conjugate with the array surface of thespatial light modulator 5, the pupil intensity distribution can beformed with a desired beam profile. This will be described below withreference to FIG. 19.

The upper drawing of FIG. 19 schematically shows, about the surfaceilluminant P22 a in the pupil intensity distribution 21 p in FIG. 7, abeam profile (cross-sectional distribution of light intensity) along across section extending in the x-direction while passing a centerthereof. In general, when the size of the reflective faces of the mirrorelements forming the spatial light modulator is relatively large, a beamprofile of each surface illuminant forming the pupil intensitydistribution tends to be a top-hat type as shown in the upper drawing ofFIG. 19.

In the present embodiment, since the diffractive optical element 3 isarranged so as to be approximately optically conjugate with the arraysurface of the spatial light modulator 5, the provision of thedivergence angle to the incident beam by the diffractive optical element3 is nothing but provision of the divergence angle to the incident beamto each mirror element 5 a of the spatial light modulator 5. Inaddition, the distribution of angular directions of emergent beams fromthe spatial light modulator 5 is converted into the positiondistribution on the illumination pupil of the entrance plane 8 a of themicro fly's eye lens 8A through the relay optical system 7.

Therefore, the surface illuminant P22 a in the pupil intensitydistribution 21 p obtained with the diffractive optical element 3 as thedivergence angle providing member being retracted from the optical pathis changed into the surface illuminant P32 a in the pupil intensitydistribution 22 p shown in FIG. 9, by the divergence angle providingaction of the diffractive optical element 3 inserted in the opticalpath. Namely, the region 32 a covered by the surface illuminant P32 acomes to have a shape resulting from similar enlargement of the regionR22 a covered by the surface illuminant P22 a, depending on themagnitude of the divergence angle provided to the incident beam F12 bythe diffractive optical element 3.

As a result, with the similar enlargement change of the contour shape ofthe surface illuminant P32 a from the contour shape of the surfaceilluminant P22 a by the divergence angle providing action of thediffractive optical element 3, the beam profile of the surfaceilluminant P32 a also demonstrates a characteristic change from thetop-hat type beam profile of the surface illuminant P22 a. Specifically,the beam profile along the cross section extending in the x-directionwhile passing the center of the surface illuminant P32 a comes to havesuch a characteristic that the light intensity gently decreases from thecenter toward the periphery, as shown in the lower drawing of FIG. 19.

The change in the characteristic of the beam profile with change of thecontour shape also applies to the other surface illuminants P31 a-P31 d;P32 b-P32 d resulting from the enlargement of the contour shape by thedivergence angle providing action of the diffractive optical element 3in the pupil intensity distribution 22 p. Furthermore, it also appliesto the surface illuminants resulting from the enlargement of the contourshape by the divergence angle providing action of the diffractiveoptical element 3 or 3 a in the other pupil intensity distributions 23p-28 p.

Furthermore, the degree of the change in the characteristic of the beamprofile with change of the contour shape of an arbitrary surfaceilluminant in the pupil intensity distribution is dependent on themagnitude of the divergence angle provided to the beam forming thesurface illuminant, by the divergence angle providing member. In otherwords, by locating the divergence angle providing member that providesthe required divergence angle to a beam forming an arbitrary surfaceilluminant in the pupil intensity distribution, in the optical path, thebeam profile of the surface illuminant can be changed into a desiredcharacteristic.

As described above, the illumination optical system (1 to 12A) of thepresent embodiment can form the pupil intensity distribution having adesired beam profile, on the illumination pupil immediately behind themicro fly's eye lens 8A. The exposure apparatus (1 to WS) of the presentembodiment can accurately transfer a fine pattern onto the wafer W underan appropriate illumination condition realized according to thecharacteristic of the pattern of the mask M to be transferred, using theillumination optical system (1 to 12A) for forming the pupil intensitydistribution with the desired beam profile.

In the above-described embodiment, the light with the inhomogeneous beamprofile emitted from the light source LS is changed into the light withimproved homogeneity of the intensity distribution by the action of thelight intensity distribution homogenizing member 2, and the homogenizedlight is incident to the array surface of the spatial light modulator 5.Namely, by the action of the light intensity distribution homogenizingmember 2, the light intensity distribution of the beam impinging on eachmirror element 5 a of the spatial light modulator 5 is homogenized and,in turn, the light intensity distribution of the beam emerging from eachmirror element 5 a is also homogenized. As a result, improvement isachieved in controllability of the spatial light modulator 5 to drivethe large number of mirror elements 5 a in forming the pupil intensitydistribution.

In the above embodiment, the light intensity homogenizing member 2 isused to supply the light with the approximately homogenous intensitydistribution to the diffractive optical element 3 a. However, forexample in FIG. 10, light beams with mutually different lightintensities may be supplied to the first region to convert the incidentbeam into the first divergent beam and the second region to convert theincident beam into the second divergent region. Here, since the firstdivergence angle of the first divergent beam is larger than the seconddivergence angle of the second divergent beam, if light with anapproximately homogenous light intensity distribution is guided to thearray surface of the spatial light modulator 5, the luminance of theregions R42 a-R42 d on the pupil generated by the second divergent beamvia the spatial light modulator 5 becomes lower than the luminance ofthe regions R41 a-R41 d on the pupil generated by the first divergentbeam via the spatial light modulator 5. In that case, light with thelight intensity of the second region of the diffractive optical element3 a larger than the light intensity of the first region can be guided tothe diffractive optical element 3 a.

A light intensity distribution setting member to be used for setting thelight from the light source to the light intensity distribution in whichthe light intensity to the second region is larger than the lightintensity to the first region of the diffractive optical element 3 awhich can be regarded as the divergence angle providing member asdescribed above, can be a combination of the relay optical system 2 bwith an element wherein a wedge-shaped optical member is provided on theexit side of each of the lens array 2 a as the wavefront divisionelement, a combination of the relay optical system 2 b with adiffractive optical element for forming a stepped light intensitydistribution in the far field, or the like.

Furthermore, the control unit CR receives supply of the monitor result(measurement result) of the light intensity distribution on the arraysurface of the spatial light modulator 5 from the beam monitor BM asoccasion demands. In this case, the control unit CR refers to themonitor result about the light intensity distribution by the beammonitor BM when needed and appropriately controls the spatial lightmodulator 5 depending upon temporal variation of the beam profile of thelight supplied from the light source LS, whereby a desired pupilintensity distribution can be formed on a stable basis.

In the above description, the lens array 2 a as wavefront divisionelement and the relay optical system 2 b are used as the light intensityhomogenizing member arranged in the optical path between the lightsource LS and the spatial light modulator 5 and configured to improvethe homogeneity of the intensity distribution of the light incident tothe array surface of the spatial light modulator 5. However, the lightintensity homogenizing member can also be configured, for example, usingan internal reflection type optical integrator (typically, a rod typeintegrator). Furthermore, the light intensity homogenizing member canalso be configured using as the wavefront division element, for example,a diffractive optical element array or a reflective element arrayobtained by replacing the plurality of lens elements of the lens array 2a with diffractive faces or reflective faces having a functionequivalent to that of these lens elements.

It is important in the light intensity distribution homogenizing memberthat the homogeneity of the light intensity distribution of the beamemerging from the member be better than that of the light intensitydistribution of the beam incident to the member, and the light intensitydistribution of the beam emerging from the member does not always haveto be perfectly homogenous. The light intensity distributionhomogenizing member may be located on the light source side with respectto a middle point of the optical path between the light source and thespatial light modulator.

In the above description, the diffractive optical element 3 is used asthe divergence angle providing member for providing the divergence angleto the incident beam and emitting it. However, without having to belimited to the diffractive optical element, or without having to belimited to this, the divergence angle providing member can also beconfigured using a refractive element, e.g., like a lens array, or areflective element, e.g., like a mirror array, or a scattering element,e.g., like a diffuser plate, or the like.

In the above description, the half wave plate 6 arranged in the opticalpath in which the partial beam of the propagating beam travels is usedas the polarizing member. However, without having to be limited to thehalf wave plate, the polarizing member can also be configured, forexample, using a quarter wave plate, an azimuth rotator, or the likearranged in the optical path in which a partial beam of the propagatingbeam travels. In other words, an element that converts the polarizationstate of incident light into another polarization state withoutsubstantial loss of light quantity can be used as the polarizing member.When the polarizing member used is one with the quarter wave plate, itcan set a polarization state of an arbitrary surface illuminant in thepupil intensity distribution to a desired elliptic polarization.

The azimuth rotator has a form of a plane-parallel plate and is made ofa crystal material being an optical material with optical rotatorypower, e.g., rock crystal. Furthermore, the azimuth rotator is arrangedso that its entrance plane (and in turn its exit plane) is perpendicularto the optical axis AX and so that its crystallographic optic axis isapproximately coincident with the direction of the optical axis AX (orapproximately coincident with the traveling direction of incidentlight). When the polarizing member is one with the azimuth rotator, itcan set a polarization state of an arbitrary surface illuminant in thepupil intensity distribution to a desired linear polarization. Here, anoptical material with optical rotatory power can be regarded as anelement that provides a phase difference between a right-handed circularpolarization component and a left-handed circular polarization componentincident to the optical material, and a wave plate can be regarded as anelement that provides a phase difference between mutually orthogonalpolarization components incident to the wave plate. In this manner, thepolarizing member can be regarded as a member that provides a phasedifference between a certain specific polarization component of lightincident to the polarizing member and another polarization component ina polarization state different from that of the certain specificpolarization component.

In FIG. 1, for easier understanding of the illustration of the entireapparatus and the action of the spatial light modulator 5, the opticalaxis AX of the reimaging optical system 4 and the optical axis AX of therelay optical system 7 are arranged to make 45° with the array surfaceof the spatial light modulator 5. However, without having to be limitedto this configuration, it is also possible to adopt a configuration, forexample as shown in FIG. 20, wherein a pair of optical path bendingmirrors MR2, MR3 are set in whereby the optical axis AX of the reimagingoptical system 4 as entrance optical axis and the optical axis AX of therelay optical system 7 as exit optical axis are arranged to make anangle smaller than 45° with the array surface of the spatial lightmodulator 5. FIG. 20 shows the major configuration along the opticalpath from the half wave plate 6 to the micro fly's eye lens 8A.

The above description shows the example in which the diffractive opticalelement 3 as divergence angle providing member is located at theposition approximately optically conjugate with the array surface of thespatial light modulator 5. However, without having to be limited tothis, the divergence angle providing member may be arranged in aconjugate space including a surface optically conjugate with the arraysurface of the spatial light modulator. Here, the “conjugate space”refers to a space between an optical element with a power adjacent onthe front side to a conjugate position optically conjugate with thearray surface of the spatial light modulator and an optical element witha power adjacent on the back side to the conjugate position. It is notedthat a plane-parallel plate or a planar mirror without power may existin the “conjugate space.”

The above description shows the example in which the half wave plate 6as polarizing member is located at the position approximately opticallyconjugate with the array surface of the spatial light modulator 5.However, without having to be limited to it, the polarizing member maybe located at a position in the vicinity of the array surface of thespatial light modulator, or in the conjugate space including the surfaceoptically conjugate with the array surface of the spatial lightmodulator.

The above description shows the example in which the diffractive opticalelement 3 as divergence angle providing member and the half wave plate 6as polarizing member are located at the position approximately opticallyconjugate with the array surface of the spatial light modulator 5 in theoptical path on the light source side with respect to the spatial lightmodulator 5. However, without having to be limited to it, the sameeffect as in the above embodiment can also be achieved, for example asshown in FIG. 21, by locating the diffractive optical element 3 and thehalf wave plate 6 at a position approximately optically conjugate withthe array surface of the spatial light modulator 5 in the optical pathon the illumination target surface side with respect to the spatiallight modulator 5. Alternatively, the half wave plate 6 may be locatedin the parallel optical path on the light source side with respect tothe spatial light modulator 5, as indicated by dashed lines in FIG. 21.FIG. 21 shows the major configuration along the optical path from theoptical path bending mirror MR2 or the half wave plate 6 to the microfly's eye lens 8A.

In this manner, the positional relationship among the divergence angleproviding member, the polarizing member, and the spatial light modulatorcan be modified in various forms. Namely, when attention is focused onthe arrangement of the divergence angle providing member, it can bearranged in the conjugate space including the surface opticallyconjugate with the array surface of the spatial light modulator in theoptical path on the light source side with respect to the spatial lightmodulator or in a conjugate space including a surface opticallyconjugate with the array surface of the spatial light modulator in theoptical path on the illumination target surface side with respect to thespatial light modulator.

When attention is focused on the arrangement of the polarizing member,it can be arranged, without having to be limited to the adjacentposition on the light source side of the divergence angle providingmember, at an adjacent position on the illumination target surface sideof the divergence angle providing member, at an adjacent position on thelight source side of the spatial light modulator, at an adjacentposition on the illumination target surface side of the spatial lightmodulator, in the conjugate space including the surface opticallyconjugate with the array surface of the spatial light modulator in theoptical path on the light source side with respect to the spatial lightmodulator, or in the conjugate space including the surface opticallyconjugate with the array surface of the spatial light modulator in theoptical path on the illumination target surface side with respect to thespatial light modulator.

However, when the half wave plate 6 as polarizing member is arranged inthe optical path on the light source side with respect to the spatiallight modulator 5 as in the above embodiment, we can enjoy the effectthat the arrangement simplifies the correspondence relationship betweenthe plurality of beams in different polarization states generatedthrough the half wave plate 6 and the plurality of mirror element groupsin the spatial light modulator 5 and in turn facilitates the control ofthe spatial light modulator 5. Furthermore, when the half wave plate 6as polarizing member is arranged in the optical path on the light sourceside with respect to the diffractive optical element 3 as divergenceangle providing member, we can enjoy the effect that the emergent lightcan be obtained in a desired linear polarization state, based on theincident light with a relatively small divergence angle.

The light intensity distribution of the beam incident to the surfacewhere the half wave plate 6 as polarizing member is arranged does nothave to be the even distribution (top-hat distribution). For example, itmay be a light intensity distribution in which light intensity varies ina direction perpendicular to the moving direction of the half wave plate6.

FIG. 22A is a drawing showing a relation between the half wave plate 6as polarizing member and the beam F1 incident to the half wave plate 6,FIG. 22B a drawing showing a light intensity distribution in anX-directional cross section of the beam F1, and FIG. 22C a drawingshowing a light intensity distribution in a Y-directional cross sectionof the beam F1.

When the light intensity distribution in the moving direction of thehalf wave plate 6 as polarizing member is nearly even, as shown in FIG.22, there is an advantage that it becomes easier to perform, forexample, control to change the position of the half wave plate 6 forchanging the areas•intensity ratio of a plurality of polarization statesin the pupil intensity distribution.

In the above embodiment, the spatial light modulator 5 capable ofindividually controlling the orientations (angles: inclinations) of thereflective faces arrayed two-dimensionally is used as a spatial lightmodulator with a plurality of mirror elements arrayed two-dimensionallyand controlled individually. However, without having to be limited tothis, it is also possible, for example, to use a spatial light modulatorcapable of individually controlling heights (positions) of thereflective faces arrayed two-dimensionally. The spatial light modulatorof this kind to be used can be one of the spatial light modulatorsdisclosed, for example, in U.S. Pat. No. 5,312,513 and in FIG. 1d inU.S. Pat. No. 6,885,493. In these spatial light modulators, atwo-dimensional height distribution is formed whereby incident light issubject to the same action as that of a diffractive surface. Theaforementioned spatial light modulator with, the plurality of reflectivefaces arrayed two-dimensionally may be modified, for example, accordingto the disclosures in U.S. Pat. No. 6,891,655 and in U.S. Pat. PublishedApplication No. 2005/0095749.

In the above embodiment the spatial light modulator 5 is provided withthe plurality of mirror elements 5 a arrayed two-dimensionally in thepredetermined surface, but, without having to be limited to this, it isalso possible to use a transmission type spatial light modulator with aplurality of transmissive optical elements arrayed in a predeterminedsurface and controlled individually.

In the above embodiment, the mask can be replaced with a variablepattern forming device which forms a predetermined pattern on the basisof predetermined electronic data. The variable pattern forming deviceapplicable herein can be, for example, a spatial light modulationelement including a plurality of reflective elements driven based onpredetermined electronic data. The exposure apparatus using the spatiallight modulation element is disclosed, for example, in U. S. Pat.Published Application No. 2007/0296936. Besides the reflection typespatial light modulators of the non-emission type as described above, itis also possible to apply a transmission type spatial light modulator ora self-emission type image display device.

The exposure apparatus of the foregoing embodiment is manufactured byassembling various sub-systems including their respective components asset forth in the scope of claims in the present application, so as tomaintain predetermined mechanical accuracy, electrical accuracy, andoptical accuracy. For ensuring these various accuracies, the followingadjustments are carried out before and after the foregoing assemblingprocess: adjustment for achieving the optical accuracy for variousoptical systems; adjustment for achieving the mechanical accuracy forvarious mechanical systems; adjustment for achieving the electricalaccuracy for various electrical systems. The assembling steps from thevarious sub-systems into the exposure apparatus include mechanicalconnections, wire connections of electric circuits, pipe connections ofpneumatic circuits, etc. between the various sub-systems. It is needlessto mention that there are assembling steps of the individualsub-systems, before the assembling steps from the various sub-systemsinto the exposure apparatus. After completion of the assembling stepsfrom the various sub-systems into the exposure apparatus, overalladjustment is carried out to ensure various accuracies as the entireexposure apparatus. The manufacture of the exposure apparatus may beperformed in a clean room in which the temperature, cleanliness, etc.are controlled.

The following will describe a device manufacturing method using theexposure apparatus according to the above-described embodiment. FIG. 23is a flowchart showing manufacturing steps of semiconductor devices. Asshown in FIG. 23, the manufacturing steps of semiconductor devicesinclude depositing a metal film on a wafer W to become a substrate ofsemiconductor devices (step S40) and applying a photoresist as aphotosensitive material onto the deposited metal film (step S42). Thesubsequent steps include transferring a pattern formed on a mask(reticle) M, to each shot area on the wafer W, using the projectionexposure apparatus of the above embodiment (step S44: exposure step),and developing the wafer W after completion of the transfer, i.e.,developing the photoresist on which the pattern has been transferred(step S46: development step).

Thereafter, using the resist pattern made on the surface of the wafer Win step S46, as a mask, processing such as etching is carried out on thesurface of the wafer W (step S48: processing step). The resist patternherein is a photoresist layer in which depressions and projections areformed in a shape corresponding to the pattern transferred by theprojection exposure apparatus of the above embodiment and which thedepressions penetrate throughout. Step S48 is to process the surface ofthe wafer W through this resist pattern. The processing carried out instep S48 includes, for example, at least either etching of the surfaceof the wafer W or deposition of a metal film or the like. In step S44,the projection exposure apparatus of the above embodiment performs thetransfer of the pattern onto the wafer W coated with the photoresist, asa photosensitive substrate or plate P.

FIG. 24 is a flowchart showing manufacturing steps of a liquid crystaldevice such as a liquid crystal display device. As shown in FIG. 24, themanufacturing steps of the liquid crystal device include sequentiallyperforming a pattern forming step (step S50), a color filter formingstep (step S52), a cell assembly step (step S54), and a module assemblystep (step S56). The pattern forming step of step S50 is to formpredetermined patterns such as a circuit pattern and an electrodepattern on a glass substrate coated with a photoresist, as a plate P,using the projection exposure apparatus of the above embodiment. Thispattern forming step includes an exposure step of transferring a patternto a photoresist layer, using the projection exposure apparatus of theabove embodiment, a development step of performing development of theplate P on which the pattern has been transferred, i.e., development ofthe photoresist layer on the glass substrate, to make the photoresistlayer in a shape corresponding to the pattern, and a processing step ofprocessing the surface of the glass substrate through the developedphotoresist layer.

The color filter forming step of step S52 is to form a color filter inwhich a large number of sets of three dots corresponding to R (Red), G(Green), and B (Blue) are arrayed in a matrix pattern, or in which aplurality of filter sets of three stripes of R, G, and B are arrayed ina horizontal scan direction. The cell assembly step of step S54 is toassemble a liquid crystal panel (liquid crystal cell), using the glasssubstrate on which the predetermined pattern has been formed in stepS50, and the color filter formed in step S52. Specifically, for example,a liquid crystal is poured into between the glass substrate and thecolor filter to form the liquid crystal panel. The module assembly stepof step S56 is to attach various components such as electric circuitsand backlights for display operation of this liquid crystal panel, tothe liquid crystal panel assembled in step S54.

The present invention is not limited just to the application to theexposure apparatus for manufacture of semiconductor devices, but canalso be widely applied, for example, to the exposure apparatus fordisplay devices such as liquid crystal display devices formed withrectangular glass plates, or plasma displays, and to the exposureapparatus for manufacture of various devices such as imaging devices(CCDs and others), micro machines, thin film magnetic heads, and DNAchips. Furthermore, the present invention is also applicable to theexposure step (exposure apparatus) for manufacture of masks (photomasks,reticles, etc.) on which mask patterns of various devices are formed, bythe photolithography process.

The above-described embodiment uses the ArF excimer laser light(wavelength: 193 nm) or the KrF excimer laser light (wavelength: 248 nm)as the exposure light, but, without having to be limited to this, thepresent invention can also be applied to other appropriate laser lightsources, e.g., an F₂ laser light source which supplies laser light atthe wavelength of 157 nm.

In the foregoing embodiment, it is also possible to apply a technique offilling the interior of the optical path between the projection opticalsystem and the photosensitive substrate with a medium having therefractive index larger than 1.1 (typically, a liquid), which is socalled a liquid immersion method. In this case, it is possible to adoptone of the following techniques as a technique of filling the interiorof the optical path between the projection optical system and thephotosensitive substrate with the liquid: the technique of locallyfilling the optical path with the liquid as disclosed in InternationalPublication WO99/49504; the technique of moving a stage holding thesubstrate to be exposed, in a liquid bath as disclosed in JapanesePatent Application Laid-open No. H06-124873; the technique of forming aliquid bath of a predetermined depth on a stage and holding thesubstrate therein as disclosed in Japanese Patent Application Laid-openNo. H10-303114, and so on. The teachings of International PublicationWO99/49504, Japanese Patent Application Laid-open No. H06-124873, andJapanese Patent Application Laid-open No. H10-303114 are incorporatedherein by reference.

In the foregoing embodiment, the present invention is applied to theillumination optical system for illuminating the mask (or wafer) in theexposure apparatus, but, without having to be limited to this, thepresent invention is also applicable to ordinary illumination opticalassemblies for illuminating the illumination target surface other thanthe mask (or wafer).

Incidentally, formation of a certain light quantity distribution (pupilshape) on the pupil plane of the illumination optical system with theuse of the spatial light modulator can also be regarded as a method forforming a certain image (light quantity distribution) by combining alarge number of microscopic patterns (microscopic regions) formed on thepupil plane by reflections from the large number of mirror elements ofthe spatial light modulator, in a predetermined array. On this occasion,because the number of mirror elements is large, a problem is, with acertain target pupil shape given, how efficiently an array of positionsof all microscopic patterns for obtaining the pupil shape (settingvalues of inclination angles of corresponding mirror elements) is to becalculated.

Furthermore, it is also possible to irradiate the array of the largenumber of mirror elements with the illumination light, for example,through a plurality of optical filters which are arranged in paralleland the respective transmittances of which can be controlled in aplurality of stages, thereby to divide the array of mirror elements intoa plurality of groups, and to control light quantities of respectivemicroscopic patterns group by group. When states such as the lightquantities of microscopic patterns on the pupil plane can be controlledgroup by group as described above, a problem is how efficiently acombination of variables about the states along with the positions ofthe respective patterns is to be calculated.

In light of such circumstances, a further problem to be solved is asfollows: in forming, for example, a target light quantity distributionor a light quantity distribution close to a target image or the like bya combination of a plurality of microscopic patterns or microscopicregions or the like, the problem is to enable efficient calculation of acombination of positions and states of the microscopic patterns or themicroscopic regions or the like.

The below will describe the second embodiment as to a control methodabout the operation of the spatial light modulator, with reference toFIGS. 25 to 31.

FIG. 25 shows a schematic configuration of the exposure apparatus EXaccording to the second embodiment. The exposure apparatus EX is ascanning exposure type exposure apparatus (projection exposureapparatus) consisting of a scanning stepper (scanner) as an example. InFIG. 25, the exposure apparatus EX is provided with a light source 10for generating illumination light for exposure (exposure light) IL, andan illumination optical system ILS for illuminating a reticle surface Ra(illumination target surface) being a pattern surface of a reticle R(mask) with the illumination light IL from the light source 10.Furthermore, the exposure apparatus EX is provided with a reticle stageRST for moving the reticle R, a projection optical system PL forprojecting an image of a pattern of the reticle R onto a surface of awafer W (photosensitive substrate), a wafer stage WST for moving thewafer W, a main control system 35 consisting of a computer for totallycontrolling the operation of the entire apparatus, various controlsystems, and so on.

The description hereinbelow will be based on such a coordinate systemthat the Z-axis is set in parallel with the optical axis AX of theprojection optical system PL, the X-axis is set along a directionparallel to the plane of FIG. 25 in a plane perpendicular to the Z-axis,and the Y-axis is set along a direction perpendicular to the plane ofFIG. 25. In the second embodiment, scanning directions of the reticle Rand the wafer W during exposure are directions (Y-directions) parallelto the Y-axis. Furthermore, the description will be based on suchdefinition that directions of rotation about axes parallel to theX-axis, Y-axis, and Z-axis (inclination directions) are defined as θxdirection, θy direction, and θz direction.

The light source 10 used herein is an ArF excimer laser light sourcewhich emits pulses of 193 nm-wavelength linearly polarized laser lightas an example. It is noted that the light source 10 applicable hereincan also be, for example, a KrF excimer laser light source whichsupplies laser light at the wavelength of 248 nm, or a harmonicgenerator which generates a harmonic of laser light emitted from asolid-state laser light source (YAG laser, semiconductor laser, or thelike).

In FIG. 25, the linearly polarized illumination light IL consisting ofthe laser light emitted from the light source 10 controlled by anunshown power supply unit travels via a transfer optical systemincluding a beam expander 11, a polarization optical system 12 foradjusting a polarization direction and a polarization state, and anoptical path bending mirror M1, to impinge as a nearly parallel beam onan illumination region 50 (cf. FIG. 27) in which a first set, a secondset, and a third set of diffractive optical element groups 19A, 19B, and19C can be set. Each of the diffractive optical element groups 19A-19Chas a plurality of diffractive optical elements (DOEs) arranged asadjacent in a direction traversing the optical path of the illuminationlight IL. A divergence angle varying unit 18 is configured including thediffractive optical element groups 19A-19C, and a drive mechanism 20 forsetting any diffractive optical elements (DOEs hereinafter) in thediffractive optical element groups 19A-19C in the illumination opticalpath, or for setting the illumination optical path in a transparentstate with no DOE being set therein.

As shown in FIG. 27, the diffractive optical element group 19A hasfirst, second, and third DOEs 19A1, 19A2, and 19A3 which are coupled soas to be able to cross a first region 51A, out of mutually approximatelyidentical rectangular first, second, and third regions 51A, 51B, 51Cobtained by dividing the illumination region 50 (illumination opticalpath) of the illumination light IL into three nearly equal sections, inthe longitudinal direction and each of which has much the same size asthe region 51A. The DOEs 19A1-19A3 are coupled to a movable portion 20Aintegrally movable along a guide portion and the movable portion 20Amoves the DOEs 19A1-19A3 in the longitudinal direction whereby it canset any one of the DOEs 19A1-19A3 in the region 51A or set the region51A in a transparent state.

Similarly, the diffractive optical element groups 19B, 19C have DOEs19B1, 19B2, 19B3 and 19C1, 19C2, 19C3, respectively, which are similarlycoupled in the longitudinal direction in the same configuration as theDOEs 19A1, 19A2, and 19A3. Concerning the DOEs 19B1-19B3 and 19C1-19C3,they can be moved in the longitudinal direction by movable portions 20Band 20C, respectively, whereby any one of them can be set in regions 51Band 51C or the region 51B or 51C can be set in the transparent state.The operation of the movable portions 20A-20C is controlled by anillumination control unit 36 under control of a main control system 35in FIG. 25. The drive mechanism 20 in FIG. 25 is configured includingthe movable portions 20A-20C.

In FIG. 27, when the regions 51A-51C are transparent, the illuminationlight IL being incident to the regions 51A-51C and consisting of thenearly parallel beam indicated by dotted lines, passes directly throughthe regions 51A-51C as illumination light IL1 indicated by a solid line.When the DOEs 19A1, 19B1, and 19C1 of a mutually identical configurationare set in the regions 51A, 51B, and 51C, the illumination light ILincident to the DOEs 19A1-19C1 is converted into illumination light IL2with a first opening angle, and it passes through the regions 51A-51C.Furthermore, when the DOEs 19A2, 19B2, 19C2 or 19A3, 19B3, 19C3 of amutually identical configuration are set in the regions 51A, 51B, and51C, the illumination light IL incident to these DOEs is converted intoillumination light IL3 or IL4 with a second opening angle (>firstopening angle) or with a third opening angle (>second opening angle),respectively, and it passes through the regions 51A-51C.

The DOEs 19A1-19A3 and others can be manufactured by forming atwo-dimensional uneven pattern of an interference fringe shape on a faceof an optically transparent glass substrate or synthetic resin substrateby a photolithography step or an embossing step or the like. The unevenpattern of the DOE 19A2 is finer than the pattern of the DOE 19A1 andthe uneven pattern of the DOE 19A3 is finer than the pattern of the DOE19A2. In the second embodiment, by setting any DOEs in the diffractiveoptical element groups 19A-19C in the regions 51A-51C or by setting theregions 51A-51C transparent, the opening angles of the illuminationlight passing through the regions 51A-51C can be set to any angle ofnearly 0, the first opening angle, the second opening angle, or thethird opening angle, independently of each other.

In FIG. 25, the illumination light having passed through theillumination region where the diffractive optical element groups 19A-19Ccan be set travels through a relay optical system 13 consisting oflenses 13 a and 13 b and then is obliquely incident at a predeterminedsmall angle of incidence to reflective faces of a large number ofmicroscopic mirror elements 16 inclination angles about two orthogonalaxes of each of which are variable, in a spatial light modulator (SLM)14. A setting surface of the diffractive optical element groups 19A-19Cand an average arrangement surface of the array of mirror elements 16are approximately conjugate with respect to the relay optical system 13.The spatial light modulator 14 (SLM 14 hereinafter) has the array ofmirror elements 16, a drive base unit 15 for supporting and driving eachmirror element 16, and an SLM control system 17 for controlling theinclination angle of each mirror element 16.

FIG. 26A is an enlarged perspective view showing a part of the SLM 14.In FIG. 26A, the array of mirror elements 16 arrayed in close proximityat constant pitches approximately in the Y-direction and in theZ-direction is supported on a surface of the drive base unit 15 of theSLM 14. As an example, the width of the mirror elements 16 is fromseveral μm to several ten μm and the numbers of the mirror elements 16arrayed approximately in the Y-direction and in the Z-direction areapproximately from several ten to several hundred. In this case, thetotal number of mirror elements 16 is, for example, approximately fromseveral thousand to 300,000.

The drive base unit 15 with the array of mirror elements 16 and thedrive mechanism corresponding to it can be manufactured, for example, byuse of the MEMS (Microelectromechanical Systems) technology. Such aspatial light modulator applicable herein is, for example, thatdisclosed in the specification of European Patent ApplicationPublication EP 779530 or in the specification of U.S. Pat. No.6,900,915. The mirror elements 16 are planar mirrors of a nearly squareshape, but the shape may be any shape such as a rectangle.

Furthermore, as shown in FIG. 28A, an array region of the array ofmirror elements 16 of the SLM 14 is divided into first, second, andthird array regions 52A, 52B, and 52C with a mutually identical width.When the total number of mirror elements 16 is N, the mirror elements 16are arranged from the first position P1 to the N1-th (N1 is an integerapproximately equal to N/3) position PN, from the (N1+1)-th position tothe N2-th (N2 is an integer approximately equal to 2N/3) position PN2,and from the (N2+1)-th position to the N-th position PN, respectively,in the array regions 52A, 52B, and 52C. The array regions 52A, 52B, and52C of the SLM 14 are approximately conjugate with the regions 51A, 51B,and 51C, respectively, where the diffractive optical element groups 19A,19B, and 19C in FIG. 27 can be set, with respect to the relay opticalsystem 13 in FIG. 25.

Therefore, the illumination light beams IL1-IL4 with the opening anglebeing set at 0 or at any one of the first to third opening anglesthrough the respective regions 51A-51C are incident to the array regions52A-52C of the SLM 14. Since the illumination light impinging on eachmirror element 16 is reflected as it is, the opening angles of theillumination light beams reflected by the mirror elements 16 in thearray regions 52A-52C of the SLM 14 are approximately equal to theopening angles of the illumination light beams having passed through therespective regions 51A-51C. It is assumed herein that the magnificationof the relay optical system 13 is approximately one.

In FIG. 25, the SLM 14 irradiates an entrance plane 25I of abelow-described micro lens array 25 with reflections from the largenumber of mirror elements 16, according to an illumination condition,thereby to form a predetermined light quantity distribution (lightintensity distribution) on the entrance plane 25I. As an example, wherenormal illumination or annular illumination is carried out, the SLM 14reflects the illumination light to form a light intensity distributionin which intensity becomes high in a circular region or in an annularregion, on the entrance plane 25I. In the case of dipolar or quadrupolarillumination being carried out, a light intensity distribution in whichintensity becomes high in two or four regions is formed; when so-calledoptimized illumination is carried out, a light intensity distribution ofa complicated shape optimized according to the pattern of the reticle Ris formed. Information of illumination conditions according to reticlesR is recorded in an exposure data file in a storage unit 39 such as amagnetic storage unit. The main control system 35 supplies informationof an illumination condition read out from the exposure data file to acontroller in the illumination control unit 36, and in accordance withthe information, the controller controls the inclination angles of allthe mirror elements 16 of the SLM 14 through the SLM control system 17and sets the DOEs selected from the diffiactive optical element groups19A-19C in the illumination optical path or set the illumination opticalpath transparent through the drive mechanism 20 (the details of whichwill be described later).

The illumination light reflected by the large number of mirror elements16 of the SLM 14 is incident along the optical axis AX of theillumination optical system ILS to an incidence optical system 21 forconverting the illumination light IL into parallel light. Theillumination light having passed through the incidence optical system 21travels through a relay optical system 22 consisting of a first lenssystem 22 a and a second lens system 22 b to impinge on the entranceplane 25I of the micro lens array 25. The average arrangement plane ofthe array of mirror elements 16 and the entrance plane 25I areapproximately in an optical Fourier transform relation. The micro lensarray 25 is an array of a large number of microscopic lens elementsarranged approximately in close contact in the Z-direction and theY-direction and an exit plane of the micro lens array 25 is a pupilplane IPP of the illumination optical system ILS (a plane conjugate withthe exit pupil). A surface illuminant consisting of a large number ofsecondary light sources (light source images) by wavefront division areformed on the pupil plane IPP (illumination pupil plane IPPhereinafter).

Since the micro lens array 25 is an array in which a large number ofmicroscopic optical systems are arranged in parallel, a global lightquantity distribution (light intensity distribution) on the entranceplane 25I is transferred to the illumination pupil plane IPP as exitplane as it is. In other words, the global light quantity distributionformed on the entrance plane 25I and the global light quantitydistribution of the whole of secondary light source are approximatelyequal or demonstrate a high correlation. Here, the entrance plane 25I isa plane equivalent to the illumination pupil plane IPP (a plane wherethe light quantity distribution is approximately similar) and a shape ofan arbitrary light quantity distribution of the illumination lightformed on the entrance plane 25I (which is a shape of a regionsurrounded by a contour line where light intensity is at a predeterminedlevel) becomes a pupil shape being a shape of a light quantitydistribution on the illumination pupil plane IPP as it is. It is notedthat a fly's eye lens may be used instead of the micro lens array 25.Furthermore, the cylindrical micro fly's eye lens disclosed, forexample, in U.S. Pat. No. 6,913,373 may be used as the fly's eye lens.

In the second embodiment, an illumination aperture stop 26 is set on theillumination pupil plane IPP. FIG. 26B shows an example of a targetlight quantity distribution 55 in a circumference 54 where the coherencefactor (σ value) set by the illumination aperture stop 26 is 1 on theentrance plane 25I (and in turn on the illumination pupil plane IPP).The light quantity distribution 55 is, for example, a distributionoptimized for the reticle R. In FIG. 25, as an example, the illuminationlight beams IL2, IL4 with the first and third opening angles from theset surface of the diffractive optical element groups 19A and 19C areincident to the array of mirror elements 16. In this case, theillumination light beam IL2 (or IL4) reflected by the mirror elements 16forms a dot pattern 53B (or 53D) (cf. FIG. 28A) being a circular smalllight quantity distribution with a second largest diameter d2 (or amaximum diameter d4) on the entrance plane 25I (illumination pupil planeIPP) of the micro lens array 25. Namely, the larger the opening angle ofthe illumination light incident to the mirror elements 16 of the SLM 14,the larger the diameter of a dot pattern of light incident to theentrance plane 25I after reflected by the mirror elements 16.

Furthermore, as shown in FIG. 27, let us suppose, for example, thatwhile no DOE is set in the region 51A in the illumination region 50 (thetransparent state) and the DOEs 19B1 and 19C2 are set in the respectiveregions 51B and 51C, the illumination region 50 is irradiated with theillumination light IL. At this time, as shown in FIG. 28A, the diametersof dot patterns 53A formed at arbitrary positions PA1, PA2 on theentrance plane 25I (and in turn on the illumination pupil plane IPP, thesame also applies to the description below) by the illumination lightIL1 reflected by arbitrary mirror elements 16A1, 16A2 in the first arrayregion 52A of the SLM 14 (region approximately conjugate with the region51A) are the minimum d1 in common. In addition, the diameters of dotpatterns 53B formed at arbitrary positions PB1, PB2 on the entranceplane 25I by the illumination light IL2 reflected by arbitrary mirrorelements 16B1, 16B2 in the second array region 52B of the SLM 14 (regionapproximately conjugate with the region 51B) are d2 in common and thediameters of dot patterns 53C formed at arbitrary positions PC1, PC2 onthe entrance plane 25I by the illumination light IL3 reflected byarbitrary mirror elements 16C1, 16C2 in the third array region 53B ofthe SLM 14 (region approximately conjugate with the region 51C) are d3in common. Furthermore, if the DOE 19A3 is set in the region 51A in FIG.27, dot patterns 53D with the maximum diameter d4 indicated by dottedlines are formed at positions PA1, PA2 on the entrance plane 25I in FIG.28.

In the second embodiment, as described above, the two-dimensionalpositions (positions in the Y-direction and the Z-direction) of dotpatterns formed on the entrance plane 25I (illumination pupil plane IPP)by the illumination light reflected by the respective mirror elements 16in the array regions 52 a, 52B, and 52C of the SLM 14 can be arbitrarilyset in a movable range including at least the region in thecircumference 54 where the σ value is 1. The two-dimensional positionsof the dot patterns formed on the entrance plane 25I by the reflectedlight from the respective mirror elements 16 can be controlled bycontrolling the inclination angles about the two orthogonal axes of therespective mirror elements 16.

On the other hand, the diameters d, which are variables about states ofthe dot patterns formed on the entrance plane 25I by the illuminationlight reflected by the respective mirror elements 16 in the arrayregions 52A, 52B, and 52C, are set to any one of d1, d2, d3, and d4 incommon for the respective array regions 52A, 52B, and 52C. Themagnitudes of the diameters d1-d4 are in the relation below and theminimum diameter d1 is set, for example, smaller than the width in thetransverse direction of the cross-sectional shape of each lens elementforming the micro lens array 25.

d1<d2<d3<d4  (1)

The diameter d of the dot pattern set in common for each of the arrayregions 52A-52C can be controlled based on which DOEs are selected fromthe diffractive optical element groups 19A-19C of the divergence anglevarying unit 18 in FIG. 25 and set in the respective regions 51A-51C ofthe illumination optical path. In the second embodiment the dot patterns53A-53D formed on the entrance plane 25I are small circles. In contrastto it, depending upon the numerical aperture of the relay optical system22 in FIG. 25 or the like, it is also possible to form dot patterns57A-57D of a nearly square shape (approximately similar to the shape ofthe mirror elements 16) with the respective widths on each side being,for example, d1-d4 as shown in FIG. 28B, on the entrance plane 25I byreflections from the mirror elements 16 of the SLM 14. The regions52A-52C of the SLM 14 may be at least two and the types of the dotpatterns 53A-53D or the like (the number of diameters or widths d1-d4)may be at least two types (e.g., only the dot patterns 53A and 53B).

In FIG. 25, a beam splitter BS1 is set between the first lens 22 a andthe second lens 22 b of the relay optical system 22 and a beam splitfrom the illumination light by the beam splitter BS1 is incident to alight receiving surface of a two-dimensional imaging device 24 of a CCDor CMOS type through a condensing lens 23. An imaging signal of theimaging device 24 is supplied to a characteristic measuring unit in theillumination control unit 36. The light receiving surface HP1 of theimaging device 24 is set in conjugate with the entrance plane 25I of themicro lens array 25 by the condensing lens 23. In other words, the lightreceiving surface of the imaging device 24 is also a surfacesubstantially equivalent to the illumination pupil plane IPP and a lightquantity distribution approximately similar to the light quantitydistribution on the illumination pupil plane IPP is formed on the lightreceiving surface of the imaging device 24. The characteristic measuringunit in the illumination control unit 36 can measure the light quantitydistribution (pupil shape) on the illumination pupil plane IPP from thedetected signal by the imaging device 24.

It is noted that a monitor device for measuring the pupil shape of theillumination optical system ILS may be set on the reticle stage RST oron the wafer stage WST. The illumination light IL from the surfaceilluminant formed on the illumination pupil plane IPP travels via afirst relay lens 28, a reticle blind (fixed field stop or variable fieldstop) 29, a second relay lens 30, an optical path bending mirror 31, anda condenser optical system 32 to illuminate, for example, anillumination region oblong in the X-direction on the reticle surface Ra,in a homogenous illuminance distribution. The illumination opticalsystem ILS is constructed including the optical members from the beamexpander 11 to the divergence angle varying unit 18, the relay opticalsystem 13, the SLM 14, the optical members from the incidence opticalsystem 21 to the micro lens array 25, and the optical system from theillumination aperture stop 26 to the condenser optical system 32. Eachoptical member of the illumination optical system ILS is supported on anunshown frame.

Furthermore, connected to the main control system 35 are an input/outputdevice 34 for exchanging information such as the illumination conditionfor the reticle R, for example, with a host computer (not shown), anarithmetic unit 40 for determining the inclination angles of therespective mirror elements 16 of the SLM for obtaining a target lightquantity distribution and the types of DOEs to be selected from thediffractive optical element groups 19A-19C, and the storage unit 39. Thearithmetic unit 40 may be a function on software of a computer formingthe main control system 35. An illumination device 8 is constructedincluding the light source 10, illumination optical system ILS,input/output device 34, illumination control unit 36, arithmetic unit40, and storage unit 39.

Under the illumination light IL from the illumination optical systemILS, a pattern in the illumination region on the reticle R is projectedat a predetermined projection magnification (e.g., ¼, ⅕, and so on) toan exposure region of one shot area on the wafer W, through theprojection optical system PL telecentric on both sides (or only on oneside, i.e., on the wafer side). The illumination pupil plane IPP isconjugate with a pupil plane of the projection optical system PL (planeconjugate with the exit pupil) and an aperture stop AS is set on thepupil plane of the projection optical system PL. The wafer W embracesone in which a surface of a base material of silicon or the like iscoated with a photoresist (photosensitive material) in a predeterminedthickness.

Furthermore, the reticle R is held as stuck on the top face of thereticle stage RST and the reticle stage RST is mounted so as to bemovable at a constant speed in the Y-direction and movable at least inthe X-direction, the Y-direction, and the θz direction, on a top face ofan unshown reticle base (plane parallel to the XY plane). Atwo-dimensional position of the reticle stage RST is measured by anunshown laser interferometer and, based on this measurement information,the main control system 35 controls the position and speed of thereticle stage RST through a drive system 37 including a linear motor orthe like.

On the other hand, the wafer W is held as stuck on the top face of thewafer stage WST through a wafer holder (not shown) and the wafer stageWST is movable in the X-direction and the Y-direction and movable at aconstant speed in the Y-direction on a top surface of an unshown waferbase (plane parallel to the XY plane). A two-dimensional position of thewafer stage WST is measured by an unshown laser interferometer orencoder and, based on this measurement information, the main controlsystem 35 controls the position and speed of the wafer stage WST througha drive system 38 including a linear motor or the like. It is noted thatthe apparatus is also provided with an alignment system (not shown) forperforming alignment between the reticle R and the wafer W.

As a basic operation in exposure of the wafer W by the exposureapparatus EX, the main control system 35 reads an illumination conditionfor the reticle R from the exposure data file and sets the readillumination condition in the illumination control unit 36.Subsequently, the wafer W is moved to a scan start position withmovement (step movement) of the wafer stage WST. Thereafter, emission oflight from the light source 10 is started and, while the wafer W isexposed with an image of the pattern of the reticle R by the projectionoptical system PL, the reticle R and the wafer W are moved insynchronism at a speed ratio of the projection magnification through thereticle stage RST and the wafer stage WST, thereby implementing scanningexposure in one shot area on the wafer W with the pattern image of thereticle R. By step-and-scan operation to repeat the step movement andthe scanning exposure of the wafer W as described above, all the shotareas on the wafer W are exposed with the image of the pattern of thereticle R under the optimal illumination condition.

Next, an example of an operation for setting the light quantitydistribution (pupil shape) optimized for the reticle R on theillumination pupil plane IPP (entrance plane 25I), in the exposureapparatus EX will be described with reference to the flowchart of FIG.29. This operation is controlled by the main control system 35. First,in step 102 of FIG. 29, the reticle R is loaded on the reticle stage RSTin FIG. 25 and the input/output device 34 implements input ofinformation of the light quantity distribution (target light quantitydistribution) on the illumination pupil plane (or on the entrance plane25I) computationally-optimized for the device pattern formed on thereticle R, into the arithmetic unit 40 through the main control system35. The input information is also recorded in the exposure date file inthe storage unit 39. Here, when a large number of grid points arrayed atpitches Δy and Δz in the Y-direction and in the Z-direction are set inthe effective area surrounded by the circumference 54 where the σ valueis 1 on the illumination pupil plane IPP in FIG. 26B, coordinates (ym,zn) in the Y-direction and the Z-direction of the n-th grip point at them-th position in the Y-direction and at the n-th position in theZ-direction with respect to a predetermined origin (ya, za) areexpressed as given below. It is noted that in the second embodiment thepitches Δy and Δz are equal but they may be different. Furthermore, thepitches Δy, Δz are set smaller than the diameter d1 of the minimum dotpattern 53A in FIG. 28A.

ym=ya+mΔy, where m=0 to M1  (2A)

zn=za+nΔz, where n=0 to M2  (2B)

M1 and M2 in these equations are integers larger than the number of themirror elements 16 arrayed in the SLM 14. At this time, the target lightquantity distribution is expressed as a set of light intensities TE(ym,zn) at all the grid points at the coordinates (ym, zn) in the effectivearea on the illumination pupil plane IPP as an example. As an example,the light intensities TE(ym, zn) are normalized so that an integratedvalue thereof in the effective area becomes 1. The target light quantitydistribution is assumed to be, for example, the light quantitydistribution 55 in FIG. 26B. The light quantity distribution 55 is alsoshown by dotted lines in FIG. 30A and FIG. 30B described below.

In the second embodiment, where the grid points at the coordinates (ym,zn) are regarded as pixels, the target light quantity distributionexpressed by the light intensities TE(ym, zn) can also be regarded as atarget image. In next step 104, the main control system 35 reads theposition information (the numbers N1, N2, and N of the positions PN1,PN2, and PN) of the groups of the j-th sets (j=1, 2, and 3) of mirrorelements 16 in the array regions 52A, 52B, and 52C of the SLM 14 in FIG.28A from the exposure data file stored in the storage unit 39, forexample, and sets the read position information in the controller of theillumination control unit 36. The main control unit 35 sets informationof the numbers N1, N2, and N, the coordinates (ym, zn) on theillumination pupil plane IPP in Equations (2A), (2B), the diametersd1-d4 of the dot patterns 53A-53D formed by reflections from the mirrorelements 16, and average light intensities in the dot patterns 53A-53D(or relative values thereof) in the arithmetic unit 40 as well.

In next step 106, the arithmetic unit 40 virtually sets center positions(yi, zi) and diameters Di (i=1 to N) of dot patterns to be formed on theentrance plane 25I (and in turn on the illumination pupil plane IPP) byreflections from the N mirror elements 16 of the SLM 14, topredetermined initial values. Values of the center positions (yi, zi)are set to any of the coordinates (ym, zn) (m=0 to M1, n=0 to M2) of thegrid points in the effective area represented by Equations (2A), (2B)and the diameters Di are set to any of the diameters d1 to d4. In fact,the diameters of the dot patterns formed by reflections from therespective mirror elements 16 in the array regions 52A-52C of the SLM 14are common, but it is assumed in this step 106 that the diameters Di ofthe dot patterns formed by reflections from all the mirror elements 16of the SLM 14 are set to arbitrary values in a variable range (from d1to d4 herein) independently of each other. The initial values of themmay be an arbitrary combination in the variable range. It is noted thatat this stage, the first to N-th dot patterns may be stored simply incorrespondence to the first to N-th mirror elements 16 of the SLM 14,respectively.

In next step 108, the arithmetic unit 40 calculates light intensitiesD1E(ym, zn) (set light quantity distribution) of all the grid pointsrepresented by the coordinates (ym, zn) in the effective area of theentrance plane 25I, from the center positions (yi, zi) and the diametersDi of the N dot patterns set in step 106. The light intensities D1E(ym,zn) are also normalized so that an integrated value thereof in theeffective area becomes 1. In the second embodiment, as an example, anobjective function f having difference information between the lightintensities TE(ym, zn) (target light quantity distribution) and thelight intensities D1E(ym, zn) (set light quantity distribution) isdefined as follows.

f=ΣΣ{TE(ym,zn)−D1E(ym,zn)}²  (3)

The additions about the integers m, n in Equation (3) are carried outover all the grid points in the effective area of the entrance plane 25I(illumination pupil plane IPP). It is noted that the objective functionf may be defined as a square root of the right-hand side of Equation (3)or the like. In next step 110, the arithmetic unit 40 determines whetherthe objective function f calculated from Equation (3) is not more than apredetermined tolerance. The tolerance is preliminarily set in thearithmetic unit 40, for example, from the input/output device 34 throughthe main control system 35. When the objective function f is larger thanthe tolerance, the operation shifts to step 112, where the arithmeticunit 40 changes the center positions (yi, zi) and/or the diameters Di(i=1 to N) of the N dot patterns set in step 106 (or in preceding step112). In this step 112, it is also assumed that the diameters Di of thedot patterns formed by reflections from all the mirror elements 16 ofthe SLM 14 can be set to arbitrary values in the variable range (from d1to d4 herein) independently of each other.

Thereafter, the operation moves to step 108, where the arithmetic unit40 calculates the light intensities D1E(ym, zn) (set light quantitydistribution) of all the grid points in the effective area of theentrance plane 25I, from the center positions (yi, zi) and the diametersDi of the N dot patterns changed in step 112, and then calculates theobjective function f from Equation (3). In next step 110, the arithmeticunit 40 determines whether the calculated objective function f is notmore than the aforementioned tolerance. When the objective function f islarger than the tolerance, the operation in steps 112, 108, and 110 isfurther repeated. On the other hand, when in step 110 the objectivefunction f is not more than the tolerance, i.e., when the set lightquantity distribution becomes approximately equal to the target lightquantity distribution, the operation moves to step 114.

The set of light intensities D1E(ym, zn) of the grid points at therespective coordinates (ym, zn) in the effective area on the entranceplane 25I (illumination pupil plane IPP) in FIG. 30A, which has beenobtained when the objective function f became not more than thetolerance in step 110, is defined as a first set light quantitydistribution 56. The light quantity distributions of FIG. 30A and FIG.30B are distributions virtually calculated by the arithmetic unit 40. InFIG. 30A, each mirror element 16 of SLM 14 can form any dot pattern outof the dot patterns 53A-53D with the diameters d1-d4 on the entranceplane 25I by its reflection.

FIG. 31A is a drawing concerning all (N) dot patterns forming the firstset light quantity distribution 56 in FIG. 30A, which shows a collectionof their diameters Di and array numbers i (i=1 to N) of the mirrorelements 16 of the SLM 14 corresponding to them. Depending upon thearray number i of each mirror element 16, the center position (yi, zi)(any of the coordinates (ym, zn)) of a corresponding dot pattern on theentrance plane 25I is specified. Then, in step 114, the arithmetic unit40 performs clustering to partition the N dot patterns forming the firstset light quantity distribution 56, into three groups each of whichincludes the same number of dot patterns as the number of mirrorelements 16 in the three array regions 52A, 52B, and 52C of the SLM 14in FIG. 28A, for example, so as to minimize the sum of discrepancies ofthe diameters Di. The clustering to be adopted in this case can be, forexample, the K-means clustering (partitional optimization method) whichis one of non-hierarchical clustering techniques. The clustering isperformed, for example, in such a manner that evaluation functions ofthe respective groups are defined as square sums of differences betweencentroids (or modes or the like) of the diameters Di in the three groupsand the diameters of the respective dot patterns in the groups and thatthe sum of these three evaluation functions becomes minimum. By theclustering, the dot patterns can be readily and accurately partitionedinto three groups.

FIG. 31B shows an example of the result of the clustering to partitionthe diameters Di of the N dot patterns in FIG. 31A into first, second,and third groups 52D, 52E, and 52F. In FIG. 31B, values I1-I2, I3-I4,and I5-I6 of number i on the horizontal axis of the respective groups52D, 52E, and 52F indicate ranges of array numbers of the mirrorelements 16 of the SLM 14 corresponding to the dot patterns belonging tothe respective groups 52D, 52E, and 52F. The center positions (yi, zi)on the entrance plane 25I of the corresponding dot patterns arespecified by the values I1-I2 and others of the array numbers of themirror elements 16. In this example, the highest-frequency values of thediameters Di of the dot patterns belonging to the groups 52D, 52E, and52F are d2, d1, and d4, respectively.

In step 114, the dot patterns may be partitioned into the three groups52D, 52E, and 52F by a technique except for the clustering, e.g., by atechnique of simply partitioning the image (set light quantitydistribution) into three groups. In next step 116, the arithmetic unit40 replaces the diameters Di of the dot patterns belonging to the threegroups 52D, 52E, and 52F, with intra-group means Dj (j=1, 2, and 3). Asan example, the intra-group means Dj are the modes of the diameters Diin the respective groups. As a result, the common diameters Dj in therespective groups 52D, 52E, and 52F in FIG. 31B are d2, d1, and d4 shownin FIG. 31C. It is noted that the array number i on the horizontal axisin FIG. 31C represents the array numbers of the first to N-th mirrorelements 16 of the SLM 14 in FIG. 28A.

When in the first set light quantity distribution 56 in FIG. 30A thediameters Di of the dot patterns belonging to the groups 52D, 52E, and52F are replaced by the common diameters Dj, a second set light quantitydistribution 56A in FIG. 30B is obtained. In next step 118, thearithmetic unit 40 sets the center positions (yji, zji) and the commondiameter Dj of the dot patterns belonging to the j-th (j=1, 2, or 3)group 52D, 52E, or 52F in FIG. 31B (the dot patterns corresponding tothe I1-th to I2-th, I3-th to I4-th, or I5-th to I6-th mirror elements16), to the center positions (yji, zji) and common diameter Dj of thedot patterns formed on the entrance plane 25I by reflections from themirror elements 16 in the j-th array region 52A, 52B, or 52C (the mirrorelement group of the j-th set) of the SLM 14 in FIG. 30B (or FIG. 28A).This means that on the horizontal axis (the array number i of the mirrorelements 16) in FIG. 31C, the region corresponding to the j-th group52D, 52E, or 52F of FIG. 31B is regarded as the j-th array region 52A,52B, or 52C.

In this case, in FIG. 30B, the diameters of the dot patterns 53B formedat the positions PA3-PA5 on the entrance plane 25I (and in turn on theillumination pupil plane IPP, the same also applies to the descriptionhereinafter) by the illumination light beams reflected by the mirrorelements 16A3-16A5 in the first array region 52A of the SLM 14 are d2 incommon; the diameters of the dot patterns 53A formed at the positionsPB3-PB5 on the entrance plane 25I by the illumination light beamsreflected by the mirror elements 16B3-16B5 in the second array region52B are d1 in common; the diameters of the dot patterns 53D formed atthe positions PC3-PC5 on the entrance plane 25I by the illuminationlight beams reflected by the mirror elements 16C3-16C5 in the thirdarray region 52C are d4 in common. In the second embodiment, the centerpositions (yji, zji) of the dot patterns can be set by the inclinationangles about the two axes of the corresponding mirror elements 16 andthe common diameters Dj (d1-d4) can be set by the divergence anglevarying unit 18.

In next step 120, the arithmetic unit 40 calculates light intensitiesD2E(ym, zn) of the respective grid points at the coordinates (ym, zn) inthe second set light quantity distribution 56A in FIG. 30B. Furthermore,it calculates the objective function f1 by replacing the lightintensities D1E(ym, zn) in Equation (3) with the light intensitiesD2E(ym, zn). Then, using as initial values the center positions (yji,zji) and diameters Dj (j=1 to 3) of the dot patterns formed on theentrance plane 25I by the respective mirror elements 16 in the j-th (j=1to 3) array regions 52A-52C set in step 118, the values of the centerpositions (yji, zji) and diameters Dj (j=1 to 3) of the dot patterns arefinely adjusted so as to make the objective function f1 smaller. On thisoccasion, the diameters Dj of the dot patterns corresponding to themirror elements 16 in the respective array regions 52A-52C can beadjusted in common only among d1 to d4. The light quantity distributionset on the entrance plane 25I in this manner is defined as a third setlight quantity distribution 56B.

By this step 120, the light quantity distribution formed on the entranceplane 25I can be made closer to the target light quantity distribution.It is noted that this step 120 can be omitted. In next step 122, thearithmetic unit 40 records the values of the center positions (yji, zji)and the common diameters Dj of the dot patterns corresponding to themirror elements 16 in the respective array regions 52A-52C of the SLM 14determined in step 120 (information of the optimized illuminationcondition) into the exposure data file in the storage unit 39 throughthe main control system 35. Since the relationship between theinclination angles about the two axes in each mirror element 16 and thecenter positions (yji, zji) on the entrance plane 25I of thecorresponding dot patterns is known and the values (d1-d4) of the commondiameters Dj correspond to the DOEs 19A1-19A3 and others in FIG. 27, theinclination angles about the two axes of the mirror elements 16 in therespective array regions 52A-52C and the types (including transparency)of the DOEs 19A1-19A3 and others set in the regions 51A-51Ccorresponding to the array regions 52A-52C may be used as theinformation of the optimized illumination condition. The information ofthe optimized illumination condition is also supplied to the controllerin the illumination control unit 36.

The controller in the illumination control unit 36 sets the inclinationangles about the two axes of the respective mirror elements 16 in thearray regions 52A-52C of the SLM 14 to the optimized illuminationcondition through the SLM control system 17 and arranges the DOEs(including transparency) in the diffractive optical element groups19A-19C according to the diameters Dj of the optimized dot patterns inthe regions 51A-51C corresponding to the array regions 52A-52C, throughthe drive mechanism 20. By this, the illumination condition of theillumination optical system ILS is optimized for the pattern of thereticle R.

In next step 124 an unexposed wafer W is loaded on the wafer stage WST;in next step 126 the irradiation of the illumination light IL from thelight source 10 is started; in step 128 the exposure of the wafer W iscarried out. On this occasion, since the illumination condition isoptimized for the reticle R, the image of the pattern of the reticle Rcan be highly accurately projected to each shot area on the wafer W bythe exposure. In addition, before the exposure is started in step 128,the characteristic measuring unit in the illumination control unit 36may measure the light quantity distribution on the entrance plane 25I(illumination pupil plane IPP) while taking in the imaging signal of theimaging element 24. If it is found by the result of this measurementthat the difference between the set light quantity distribution and thetarget light quantity distribution (or difference in a specific portion)exceeds a predetermined tolerance range, the controller in theillumination control unit 36 may adjust the inclination angles about thetwo axes of the respective mirror elements 16, for example, so as tofinely adjust the positions of the dot patterns from the respectivemirror elements 16 in the array regions 52A-52C of the SLM 14.Furthermore, the types of DOEs set in the regions 51A-51C may be changedfor the respective array regions 52A-52C as occasion demands, thereby toadjust the diameters of the dot patterns for the respective arrayregions 52A-52C. This allows, for example, the illumination condition tobe optimized in real time and the exposure to be performed with highaccuracy, for example, even in the case where the pupil shape is changedby irradiation energy of the illumination light IL.

The effects and others of the second embodiment are as described below.

The exposure apparatus EX of the second embodiment is provided with theillumination device 8 for irradiating the reticle surface Ra(illumination target surface) with the light through the plurality ofmirror elements 16 (optical elements) of the SLM 14. Furthermore, themethod for forming the light quantity distribution as an image on theillumination pupil plane IPP by the illumination device 8 can also beregarded as an image forming method. This light quantity distributionforming method (image forming method) has: step 102 of setting thetarget light quantity distribution 55 (target image) on the illuminationpupil plane IPP; and steps 106 to 112 of, concerning the N (N is aninteger two or more orders of magnitude greater than K) dot patterns 53Aand others (local regions) the respective positions of which can becontrolled on the illumination pupil plane IPP and which are partitionedinto three groups (in the case of K=3) for each of which the diameter asan example of the states of the dot patterns can be controlled, changingthe N values (yi, zi) of the positions (center positions) and the Nvalues Di of the diameters thereof on the illumination pupil plane IPPand determining the N first values (yi, zi) of the positions and the Nvalues Di of the diameters so as to make smaller the value of theobjective function f corresponding to the error between the first setlight quantity distribution 56 (first image) obtained by arranging the Ndot patterns 53A and others on the illumination pupil plane IPP, and thetarget light quantity distribution. Furthermore, the light quantitydistribution forming method (image forming method) includes steps 114,116 of determining the second values Dj of the diameters and the secondvalues (yji, zji) of the positions for the three respective groups fromthe N values Di of the diameters.

Furthermore, the illumination device 8 is provided with the input/outputdevice 34 for implementing the input of information of the target lightquantity distribution (target image) on the illumination pupil planeIPP; the SLM 14 with the N mirror elements 16 which guide the light fromthe light source 10 to the respective dot patterns 53A and others (localregions) at positions variable on the illumination pupil plane IPP andwhich can be divided into the mirror element groups in the three (K=3)array regions 52A-52C; the three diffractive optical element groups19A-19C (filter portions) for controlling the diameters of the dotpatterns 53A and others in the three groups guided to the illuminationpupil plane IPP by the three mirror element groups, group by group; thearithmetic unit 40 for determining the N first values of the positionsand the N values Di of the diameters of the dot patterns 53A and others,depending on the error between the first set light quantity distribution(first image) obtained by arranging the N dot patterns 53A and others,and the target light quantity distribution, partitioning the N dotpatterns into the three groups 52D-52F according to the N values of thediameters Di, and determining the common values Dj as values of thediameters Di for the three respective groups; and the condenser opticalsystem 32 for illuminating the reticle surface Ra with the light fromthe second set light quantity distribution formed on the illuminationpupil plane IPP while setting the positions of the corresponding dotpatterns for the three respective mirror elements and setting thediameters to Dj.

Since in the second embodiment the diameters as the variables about thestates of the dot patterns can be controlled group by group for thethree groups corresponding to the array regions 52A-52C, the number ofvalues of the diameters is three (in the case of K=3), but if the numberof values of the diameters is set to three from the beginning there is apossibility that the values of the diameters have little variation fromthe initial values, for example. Then, in steps 106 and 112, thecondition is relaxed by setting the number of values of the diameters toN larger than three and three values are determined from the N values,so as to allow efficient and accurate determination of the values of thediameters, whereby the light quantity distribution (image) close to thetarget light quantity distribution (target image) can be set on theillumination pupil plane IPP.

In the second embodiment, steps 106 and 112 are arranged to set thenumber of values of the diameters of the dot patterns to the same N asthe number of mirror elements 16, but the number of values of thediameters of the dot patterns may be set to N1 (N1 is an integer notmore than N and larger than K). This means, for example, that the arrayof mirror elements 16 is divided approximately into N/2 groups and thediameters of the dot patterns corresponding to the mirror elements 16 inthe respective groups are set to common values (d1-d4).

The illumination method of the second embodiment has: forming the lightquantity distribution of the light from the light source 10 based on thetarget light quantity distribution, on the illumination pupil plane IPPwith the use of the light quantity distribution forming method (imageforming method) by the illumination device 8 of the second embodiment;and guiding the light from the illumination pupil plane IPP through thecondenser optical system 32 to the reticle surface Ra. Furthermore, theexposure method of the second embodiment uses the foregoing illuminationmethod.

Furthermore, the exposure apparatus EX of the second embodiment is theexposure apparatus for illuminating the pattern of the reticle R withthe illumination light IL for exposure and implementing the exposure ofthe wafer W (substrate) with the illumination light IL via the patternand the projection optical system PL, which is provided with theillumination device 8 of the second embodiment and which is configuredso that the pattern is illuminated with the illumination light IL by theillumination device 8. Since the second embodiment allows the pattern ofthe reticle R to be illuminated readily under the optimized illuminationcondition, the wafer W can be exposed with the image of the pattern ofthe reticle R with high accuracy.

The foregoing second embodiment uses the SLM 14 in which the inclinationangles about the two orthogonal axes of the mirror elements 16 can becontrolled for setting the light intensity distribution (light quantitydistribution) on the entrance plane 25I or on the illumination pupilplane IPP. However, the second embodiment is also applicable to a casewhere the spatial light modulator with an array of mirror elements aposition in a normal direction to a reflective face of each of which canbe controlled is used instead of the SLM 14. Furthermore, the secondembodiment is also applicable to a case where, for example, an arbitrarylight modulator with a plurality of optical elements a state (reflectionangle, refraction angle, transmittance, or the like) of incident lightto each of which can be controlled is used instead of the SLM 14.

In the aforementioned second embodiment, the diameters (or widths) ofthe dot patterns are used as the variables about the states of therespective groups of dot patterns. However, light quantities may be usedas the variables about the states. In this case, we can use opticalmember groups in each of which a plurality of ND filters with differentlight transmittances are coupled, instead of the diffractive opticalelement groups 19A-19C. Furthermore, the apparatus may be configured tosimultaneously adjust the diameters and light quantities of the dotpatterns. In the second embodiment, the divergence angle varying unit 18was configured with the diffractive optical element groups 19A-19C, butthe divergence angle varying unit 18 can also be configured by use of anarray of refractive optical elements such as a micro lens array or anarray of reflective optical elements such as a mirror array, instead ofthe diffractive optical elements.

Furthermore, in the foregoing second embodiment, the setting surface ofthe diffractive optical element groups of the divergence angle varyingunit 18 and the average arrangement surface of the array of mirrorelements 16 were approximately conjugate with respect to the relayoptical system 13, but the setting surface of the diffractive opticalelement groups of the divergence angle varying unit 18 may be located ata position off the plane conjugate with the average arrangement surfaceof the array of mirror elements 16 with respect to the relay opticalsystem 13. For example, in the example of FIG. 25, the divergence anglevarying unit 18 may be arranged in the optical path between the relayoptical system 13 and the array of mirror elements 16.

Furthermore, the above second embodiment uses the micro lens array 25which is the wavefront division type integrator in FIG. 25, as anoptical integrator. However, the optical integrator to be used may be arod type integrator as an internal reflection type optical integrator.Moreover, in manufacture of electronic devices (micro devices) such assemiconductor devices by use of the exposure apparatus EX or theexposure method in the above second embodiment, the electronic devicesare manufactured, as shown in FIG. 32, through step 221 of performingdesign of functions and performance of devices, step 222 ofmanufacturing a mask (reticle) based on the foregoing design step, step223 of manufacturing a substrate (wafer) as a base material of devices,substrate processing step 224 including a step of exposing the substratewith a pattern of the mask by the exposure apparatus EX or the exposuremethod of the aforementioned second embodiment, a step of developing theexposed substrate, and heating (curing) and etching steps of thedeveloped substrate, device assembly step (including processingprocesses such as dicing step, bonding step, and packaging step) 225,inspection step 226, and so on.

In other words, the above device manufacturing method includes the stepof exposing the substrate (wafer W) through the pattern of the mask,using the exposure apparatus EX or the exposure method of the abovesecond embodiment, and the step of processing the exposed substrate(i.e., the development step of developing the resist on the substrate toform a mask layer corresponding to the pattern of the mask on thesurface of the substrate, and the processing step of processing (heatingand etching or the like) the surface of the substrate through the masklayer).

Since this device manufacturing method can implement highly accurateexposure with the pattern of the reticle, it can implement highlyaccurate manufacture of electronic devices. It is noted that the presentinvention can also be applied to the liquid immersion type exposureapparatus, for example, as disclosed in U.S. Pat. Published ApplicationNo. 2007/242247 or in European Patent Application Publication EP1420298. Furthermore, the present invention can also be applied to thestepper type exposure apparatus.

The present invention is not limited to the application to themanufacturing processes of semiconductor devices, but can also begenerally applied, for example, to manufacturing processes of liquidcrystal display devices, plasma displays, etc. and to manufacturingprocesses of various devices (electronic devices) such as imagingdevices (CMOS type, CCD, etc.), micro machines, MEMS(Microelectromechanical Systems), thin film magnetic heads, and DNAchips.

As described above, the present invention can be carried out in avariety of configurations without departing from the spirit and scope ofthe present invention, while not having to be limited to the abovesecond embodiment.

REFERENCE SIGNS LIST

-   -   1 beam sending unit    -   2 light intensity homogenizing member    -   3 diffractive optical element (divergence angle providing        member)    -   4 reimaging optical system    -   5 spatial light modulator    -   6 half wave plate (polarizing member)    -   7 relay optical system    -   8A micro fly's eye lens (optical integrator)    -   9 polarization conversion unit    -   10A condenser optical system    -   11A mask blind    -   12A imaging optical system    -   LS light source    -   DTr, DTw pupil intensity distribution measuring units    -   CR control system    -   mask    -   MS mask stage    -   PL projection optical system    -   W wafer    -   WS wafer stage

1. An illumination optical system for illuminating an illuminationtarget surface with light from a light source, the illumination opticalsystem comprising: a spatial light modulator having a plurality ofoptical elements arrayed on a predetermined surface and individuallycontrolled, the spatial light modulator being configured to variablyform a light intensity distribution on an illumination pupil of theillumination optical system; a divergence angle providing memberarranged in a conjugate space including a surface optically conjugatewith the predetermined surface, the divergence angle providing memberbeing configured to provide a divergence angle to an incident beam andemit the beam; and a polarizing member arranged in a predetermined spaceincluding the predetermined surface or in the conjugate space, thepolarizing member being configured to change a polarization state of apartial beam of a propagating beam propagating in an optical path. 2-66.(canceled)